Well, I forgot about our email conversation and built freecad 0.15 for f20 & f21...

Needless to say, it's having issues.

Is there any reason not do go ahead and rebuild SoQt against Coin3 on both? My repoquery-fu isn't that great but I don't see much in the way of dependencies:

# repoquery --whatrequires "libSoQt.so.20()(64bit)"
SoQt-devel-0:1.5.0-12.fc21.x86_64
freecad-0:0.14-3.fc21.x86_64
python-pivy-0:0.5.0-8.hg609.fc21.x86_64

And for python-pivy:
# repoquery --whatrequires python-pivy
freecad-0:0.14-3.fc21.x86_64
freecad-0:0.15-1.fc21.x86_64

Thanks,
Richard