@trs96,
Yep I completely agree with you on this, thats why i recommended F20 in my post.
For me F20 is stable and pretty complete. I do seem to remember reading a few posts a year or so ago, where one or two users encountered issues with F21 (i think it may have been to do with PCIe dGPU but don't quote me on that), I seem to remember that they tried to downgrade to F20 but no dice due to the new format of F21+.
Since then I've avoided going any higher than F20.
All that said I'm sure there are systems out there running F21 without issues but I'm sticking F20 for now.
Cheers
Jay