Wonder where you can set that before exporting?  I did not see such thing.
Got a ticket open with support as regards those error popups. 

Reviewing the DAZ help files I found this
 NOTE! The LOD levels can be exported in any format currently available in Studio, however, only the currently selected mesh level will be exported. This means that the figure cannot be exported as a CR2 file with the LOD levels intact.

As Daz creates a resolution level called "decimator working"  alond side the base mesh, when you decimate.  So I guess if you select the decimated  level then export the figure. . you can import the result with the base level having been stripped away during the export.. 
I haven't tried it  but it could be tested by doing the above then comparing the mesh sizes of the original with the decimated version.
It's unclear whether during the export  to FBX  people are selecting the decimated level before hand. Also if you are measuring the success of your decimation using the size of the Daz scene file dont.as studio holds all LOD detail meaning the more times you decimate within a scene the more copies you make of the figure and the bigger the scene files will be.

Don't attempt to import and entire scene. 3dxchange will always have trouble importing "huge" files.
Characters... I import them by themselves and map the bones.
Props and Accessories..... I import them by themselves, to ensure proper pivot axis.

FBX is the format.... and "Use the 2011 or 2012 version."

it's an exported file from Daz to FBX /FDX  (Whatever the name is for Autodesk)
I'll have to upload it somewhere since it's a huge file
it works for smaller files, but some of them it just comes up with that after a while.

What is the Data Format?
Can you send your file to RL Support. They will tell you what's wrong.

Ok, your settings are correct.
Now you need take a screen-shot or post the error message. (word for word) please.

There is only so much that can go wrong and the people here are very knowledgeable and willing to help you.
You almost got it.

Not sure what error that is..  3DXhange comes with it after a while it's doing it's thing, then it just pops up.
Something about unsuspected format 
I checked the settings, and they are set to Base already.

Slow down. Vidi explained how your vertex count can increase. Did you make sure your settings are correct?
What's this unrecognized format?

Good Luck

I made some smaller ones, that are only 200 - 300 Mb.  
And it's importing, but at the end I get an unexpected format not being recognized.
Maybe it's just the Scene that I am trying to do..
Gonna move on to something else.. Wasted 3 days on this.
Still didn't get the time to look into Iclone 7 lol...  bought it but never played with it, only watching the training videos that came with it.