greetings.  I recently completed my 5th sleep study...well, technically sixth...
0. UARS diganosis (6/01) (no "treatment" after this...just a "you have UARS, have a nice life")
1. OSA diagnosis  (12/06) (RDI 27)
2. titration to 9cm (1/07) (start CPAP)
3. titration to 12 cm (5/07)
4. titration to 14 cm (8/07)
5. titration to 16 cm (8/08)

So started CPAP 1/2007 and have been faithfully using it (once I got a mask that didn't shred my nose).  I am no longer completely and utterly exhausted...rather I'm seemingly tired all the time (still).  What seems remarkable to me is that none of my sleep studies have reported any stage 3 sleep.  But I've read that stage 3 sleep is required for "restorative feelings"--I can believe it based on how I feel.  I hit all of the other stages.  

I have a Respironics M-series and the software (both Respironics and James R Skinner's Encore Pro Analyzer)--it reports that still have *some* apneas.  Some nights, it's basically clear.  Other nights, I have bursts with many apneas/hypopneas, but still my "average" AHIs are less than 5 for the night.  High percentages of "variable breathing" (40-70%), but never any "non-responsive" apneas.  I'm not obsessed with the values, but prefer a more qualitative approach of assessing how I feel.  I maybe download the numbers once every week or so, but if I feel like an exhausted zombie, I may take an immediate look and usually the numbers "validate" that the previous night's sleep was interrupted--lots of apneas (or maybe I disconnected my mask which doesn't happen often).  

Anyone have any thoughts?  Similar experiences?  I'm willing to send my data if it would help.  
Cheers,
SistineKid