The only place I have ever come across the audio engine dropping out is with SONAR, if it wasn't for SONAR I wouldn't even know about the audio engine dropping out. You can even change your audio interface buffer settings with Studio One open and it keeps on trucking (as does REAPER) do that in SONAR and it's drop out time every time. Ever wonder why there was a designated button to restart the audio engine in SONAR? I did, and I know why.
As to the sound, don't know if I can explain it, but anyway, what I found is using exactly the same settings things just sounded louder in SONAR (and REAPER) without adjusting anything external or internal to match it, to put it another way, if I recorded a guitar track, all faders at zero etc, same plugs and settings, no changes anywhere to monitoring level or anything, playing back SONAR (and REAPER) would be noticeably louder than Studio One, but if you mixdown there is no difference.
I can get a far better sound with Studio One, which I couldn't match with SONAR or REAPER no matter what I tried, and it's because of the Mix Engine Fx in Studio One, the Console shapper, and even better (much better) if you buy CTC-1 Pro Console Shapper, I find that to be awesome. Not to be confused with SONARs Pro Chennel as a lot of people do, they are nothing alike, Pro Channel is just a glorified FX bin sitting on top as it were, Mix Engine Fx are applied deep within the audio/summing engine of Studio One, not just sitting on top as normal Fx, it's pretty awesome when you get your head around it, I don't ever not use it. Softube also make a Tape emulation which is Mix Engine Fx compatible and is pretty awesome. It is rumored that other developers are making Mix Engine Fx plugins, but I don't think any others have surfaced yet, but I am more than happy with CTC-1 Pro and Softubes Tape, awesome stuff.