I have good experiences in general with UAD hardware and software. They have had a few glitches, as do many software companies, which is frustrating when time is money (or creativity). That said, some UAD plugins have a limit on the sample rate they will process. For instance, in a session at, say 176 kHz or 192, the Manley Vari-Mu will down sample to 48 or 96 kHz ( I forget which). This was a deliberate decision by UAD to limit required processing power while maintaining sonic integrity, but it is not published and I only found this out because I noticed it during a mix. I happened to be watching an RTA for no particular reason during a 176 kHz project (don’t ask me why it was done at that rate). I contacted UAD and Manley and was told why this happens.
I’m otherwise happy with UAD, except we have bought into a Shark-based system that is long in the tooth.
While we have analog hardware that works for half a century, digital stuff is lucky to last a few OS updates….