Here are my issues.

1. My workflow demanded that Body Mesh UV must be edited before the UVs of multiple Meshes got combined.
Since CC3 is primarily not a modeling tool, its understandable that UV Editing Tool is not included.
However, this does not justify the inability to apply new UV from re-imported edited Mesh.
As such, even though CC3 Mesh combining feature is really good, it became totally useless for me.

2. I'm making more than 10 characters concurrently.
Thus, I need to be able to compare all of the Characters at once.
But because CC3 only allowed one Avatar,
I have to load the Avatars again and again just to confirm minor changes.
This, plus the loading time on each avatar, really add up to unnecessary workloads and frustration.
Please include the feature to display Multiple Avatars.

3. Creating Custom Morphing for specific Body Part is very inconvenient.
Let's say that I have Avatar A and B, and they have totally different Body Structure.
Now, I want to morph just A's Head to B Head.
I couldn't figure out how to do it, and had to resort to manually edit it in other 3D Tools instead.

4. Because I need to add additional Joints, such as on tails or skirts,
I ended up having to export to other 3D Tools to finish things up instead.
Please add feature to add additional joints.

5. Finger Joints are an overkill in my Game, I need the Avatar to be able to make weapon grasping hand,
Freeze the Mesh, then deleted all of the finger Joints.

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6. THIS ONE IS SERIOUS
Please see the image,

I'm using XSI7 as my main 3D Tools.
Because it is very old, it cannot handle new FBX version.
+ Autodesk FBX Converter cannot handle new FBX too.

After exporting from CC3,
I had to downgrade FBX to below 2013 via 3DXChange5,
Then downgrade again to FBX2009 via FBX Converter.

Considering that I have to work on more than 10 characters concurrently, It is a real hassle to go through.
This is not just an issue with XSI. Several older tools and engine have this issue as well.
Please add choices of FBX ver on export.

Also, because the above process won't work if 3DXChange5 got skipped,
+ there is no guarantee that 3DXChange7 will output FBX2013 or below,
I will not upgrade my iClone license to 7,
BECAUSE DOING SO COULD RISK DESTROYING MY ENTIRE WORKFLOW.