i was used maya in past and actual use 3dmax, i am a autodesk user.. so i believe i can help you with somethings
first. as a icloner you are putting at side the most powerfull thing from iclone- CHARACTER ANIMATION. the problem is the comunity just dont use
the actual iclone animation tools. with curve editor you can get same result as maya with a more easy to use tool. make a landscape is a problematic point cause inside maya or 3dmax you will work with confort in a very complex terrain and when go to convert to iclone you will be very dissapointed cause iclone will cannot deal with the terrain. i make some tests recently using mudbox to sculpt a terrain and import it on iclone and its good cause mud offer tools to retopo and reduce mesh. and you can paint the terrain on substance painter giving very nice results. vegetation - well for any gameengine is not smart use meshs for trees. native speed tree billboards are the best solution to make complex and rich enviroment. about characters.. i dont know if want to create characters on iclone and animate on maya , but if you do that will not be smart cause iclone generate a riged character without ik rig controls, is a basic rig so you want to create your own. in iclone you have IK reaction by default so.. in my workflow i only create a character outside iclone if it will be a non human character like animals, talking things cartoons etc. The best thing on iclone is just the fact i create a simple rig on 3dmax and iclone create IK reactions for me, its almost a autorig setup.
You're assuming an awful lot in your post and some of the things you're talking about just aren't accurate at all. I never said anything about the tools that I use to create the scenes that I'm talking about because they're simply not relevant to the question. But since you raised the issue, I'll address them. I use DAZ Genesis 3 and Genesis 8 more often than not, and I could bring them into Iclone, sure but doing so adds a lot of extra steps that are tedious and for the time being, not well thought out. As it stands now, I can use fully rigged Genesis 8 and 3 Characters in Maya with not only Human IK, but also all of their JCMs, so why would I want to move them to Iclone and lose all that functionality? Sure, I can export them with the JCMs if I set up some export rules to include them, but they don't directly transfer into Iclone. If I want to engage them, I can't use them without first exporting each morph and then re-importing the morphs to the Morph Animation section of Iclone. If it was just one or two morphs, it would be okay but there are over two dozen per character, so if I want it to work like it does in Maya, then I'm going to spend a lot of extra time just importing and exporting morphs, which I am not doing. You also make it sound like Maya doesn't have a graph editor --it does:
It works in the same fashion IClone does, so I'm not seeing the advantage of using Iclone's over Maya's if I'm already working in Maya.
Even with all that being said, working in Iclone means I'm stuck using Iclone facial controls which are not a one to one conversion of the face bones of the Genesis 3/8 figures --I'm losing functionality on bones and morphs as well as setup time. There are no face rig controls in the viewport in Iclone, so tweaking expressions requires a lot of back and forth to the Face Puppeteer Window --which I don't care for either. In Maya I have full control of my figures and am free to rig controls as they suit me instead of being forced to adopt someone else's view of how rigging/animation should be done --I can even make dependencies via the pose editor or set driven keys. You mentioned Human IK, which IClone has licensed from Autodesk, but what we don't have right now is viewport controls for using them. I'm back and forth to another puppeteer window --which I don't care for. I've timed it and I can take a fully rigged character with all of it's joint controlled morphs from DAZ to Maya in 11 minutes --that's including the mistakes I made in the procedure.
Speedtrees are nice, but they fall short in a lot of respects. You can't edit the look of the trees so I'm stuck with their default looks. If I want to make them look stylized, then I'm out of luck. I can make trees in Maya and set their materials as needed and if I want to make animated billboards of them, I can also do that in Maya --and it looks exactly how I want them to look.
If I want to place them, I can use paintfx to place them which offers me more flexibility because I can plant more than one species at a time and literally paint them on the terrain. Speedtrees won't place on non-height-mapped terrain, which is another limitation in IClone that I don't want to deal with.
The Terrain modeling you're talking about, you assumed that I was modeling terrain in Maya. I'm not. I use World Creator 2 to create my terrains because it's designed to do just that and I have greater control because it's specialized for creating terrain. Once I'm finished creating the terrain it's simple to re-mesh and create normal maps for as well as the material masks all in the World Creator interface, so why would I want to use a program that doesn't have half the terrain creation features of World Creator 2?
Even when it comes to animation, I have my reasons for not wanting to use IClone. As of right now, IClone's capabilities for animation are easy to use if you're stringing together pre-made clips, but Maya's tools are more robust and I don't have to deal with foot sliding because of plugins like the Tween Machine(Free) and Sliding Foot Fixer 0.0.1 for Maya(Also Free). Not to mention that Maya has tools to Making locomotion for non human characters like dogs or horses because right now there are no IK tools for animating animals --so if I want to include wolf pouncing or missing an attack and sliding into a tree, then I'm forced to try doing it bone by bone because we don't have any tools to create rigs of our own inside of IClone. With plugins like Studio Library(Also Free) and BH_PathAnim($30) along with Rapid Rig Modular ($99), I am not bound by any constraint when it comes to creating and animating what I want to.
The Appeal to IClone for me is PopcornFX, Popvideo 3 and Character Creator 3. I can quickly mock-up background characters that are ready to animate quickly and efficiently Since they're already HumanIK they setup quickly in Maya and are ready to go with just a little coaxing. Character Creator 3 makes it so that I can clothe them and setup the weight maps for those background characters quickly. I like the simplicity of Iclone's PBR materials and I'm keenly interested in the upcoming human shaders. The other thing that I like about Iclone are in the physics toolbox. I was never fond of mechanical animating and IClone makes it a lot less painful to do. I'm keen to try out the improvements to the toon render because I like heavily stylized environments. IClone has a lot to offer as a rendering platform, but for me it's animating limitations make it unsuitable for the way that I like to work.
I understand you prefer to use IClone. I do think that Iclone has a lot of advantages, but the things that it doesn't have make it impractical to use for the way that I work. If that changes at some point then I don't mind saying that I'd be happy to switch but for right now, it's not the right tool for me when it comes to animating. You create your environments in Max, and that's fine --I don't like 3DS Max so everything you listed doesn't really change my mind. My question remains what it was at the start, so I think what I'll do is create a test animation in Maya tonight with morphs and all, and see if I can bring it into Iclone and render it without a lot of fuss and muss. I was just wondering if anyone else had tried it this way.