I'm working with a 5 track project with compressors, EQs and Perfect Space at 48 sample buffer and 3.5 msec round trip and I'm not getting any pops. I couldn't do this a month ago.
 
Also, for RME Users, there is still some slight latency when you click the Record Enable button. It's maybe 1 second per click (so I'll still use quick groups when enabling 10 tracks). Also, there is a slight click sound now that didn't occur in X2.

Perfect space is 32 bit and also adds latency to the project. Try disabling PS before enabling the record and see if that corrects the delay.
 
IIRC Delay compensation plugs are problematic during the recording phase of a project. I've been down that road before.

Thanks Tom!
 
This delay seems to be RME specific and isn't related to Perfect Space (although I know Perf Space adds latency to the round trip).
 
When I turn off Perfect Space, I can still work at a 48 sample buffer. That's just so awesome!! and the computer is as cool as a cucumber.
 
:-)
 
But the delay when clicking the record enable button is still present. Clicking 24 tracks one at a time to record enable takes about 25 seconds in both X1 and X2 when I move my fastest.

Further, I'm no longer getting dropouts when iterating through screen sets at low sample buffers. I used to turn up my sample buffers to 2048 to avoid issues. on a 5 track project, I'm able to flip screensets at 48 samples. I just tried a 16 track project with lots of FX and got a dropout, but in general the engine seems more efficient.
 
Like - NOTICEABLY more efficient -- so a human like me can measure it in experience.