Just got some help from the folks at DAZ regarding CC3.0,

Apparently, the only cr2's it will auto convert to V4 are those designed for V3 (my first tests I was trying Aiko to V4, Jessi to V4, etc).  I just tried a couple of things, and it does work when you use auto convert from V3 to V4, but that is the only kind of clothing it supports the auto feature at this time.  Conversion time for a V3 bodysuit to V4 was about 3-4 mins, and it required very little tweaking.

So, to amend my previous post, CC 3.0 does support auto convert from V3 to V4, but that is the only kind of source cr2 it allows for a V4 conversion.  Others need to be manually adjusted (which the application does seem to do, just takes time and learning the interface).

Still working with it, after I get the hang I'll try and post a couple of screenies showing some V3 auto converts to V4 before tweaking.