Having the ability to squeeze all textures to a single material works awesome for game asset, but it takes lots of the details out if you want to be up close and personally in the unreal engine.

How about a UDIM based single material where you can :
1) adjust the settings of the material for individual textures via unreal material pararmeters
2) adjust the UDIM texture sizes. (we dont need 2k texture for eye lashes).

this leads to the obvious:
1) high textured character
2) low draw call for unreal. This method could be used for iclone animation as well.