Also back on V3.3 for now. Also using Sonar HS4- but I really like n-Track for recording into. I just don't spend much time with it after that.
V.4 was annoying, mostly. I don't have time for the bugginess, really- losing waveforms and screens going blank. I need to get in, do it, and get out. And if I'm doing something that takes a lot of time/work, n-Track has definitely been out of the ballpark.
But that's just me, I'm no wizard... I'd go back for v.5 though, if it proves to be very stable.