I've been following this debate a while, since I had problems with audio glitches and dropouts.
I have a Macbook Pro Retina, Mid 2014, using RME UCX with USB driver v.2.23. I used to have El Capitan OSX installed, but had audio issues. So I eventually opted to install the latest OSX High Sierra 10.13.4, and installed the latest RME driver 3.07 - hoping it would help. Unfortunately that wasn't the case - still had the same glitches all the time.
But then Apple released a High Sierra update on the 23rd of May, which helped tremendously with the glitches. But last week, the glitches suddenly happens all over again, while sitting in a session with an artist. So I updated to the latest RME driver 3.08 and the newest High Sierra update on the 8th of June, but the glitches didn't change - they still appear randomly about every 10 min and destroys my sessions. It also appears just listening to Spotify and Youtube.
This is so annoying, that you can't get it fixed. I've battled this problem intensively for a whole month now - I don't trust my RME soundcard any more. It has run 100% reliable without any problems for 5 years, but now my patience is about to run out! Maybe it's an Apple/RME problem, since it helped for about a week with the Apple Security update....but stil....
Please fix this issue ASAP!! :-(