Didn't really want to but it was a bit of a Hail Mary. Something caused my UAD devices to not work in 8.1 anymore. This happens occasionally - when they are working they are rock solid but when the drivers get knocked out - yikes.
 
So all attempts FAILED - for both my PCIe cards and my Apollo Firewire. I figured that since you can rollback your install, and the fact that 8 isn't officially supported either for UAD, I had little risk seeing what would happen.
 
Let Windows 10 install over night, this morning I ran the UAD installer and it installed two of my three devices. No worries there - I know this game. I will remove the one UAD PCIe card, boot, turn off, put card back in, boot again, and all should be well.
 
So, it seems that the install of Windows 10 actually FIXED my UAD driver issue.
 
I'll post more here if anything changes...

Win 10 has be great for me so far.  I don't use UAD stuff, but Sonar is ripping away.  Only took about 2 hrs per computer to install 10 for me.

Got the other UAD card working no problem (seems you have to install it first). :)
 
So far, I'm liking it and everything seems to be working just fine...