Vastman
I decided to try Ableton and Studio One2 just for the heck of it but ended up extremely frustrated after a couple weeks...so many things X3 allows/enables or which are just intuitive to me now....do not appear possible; I became frustrated very fast. I came away feeling S1/2 was more a toy than my ideal DAW... Now whether this is true or that I haven't "immersed" myself enough in the others to see their genius, I don't know...Studio one really seemed limited and Live just was so different...
Actually I think you've nailed the differences quite well. Of course this is all subjective, but I feel Studio One - despite being a capable and sleek program - is not as ambitious as Sonar in trying to suit a wide variety of applications. It does have the mastering page thing, which is really genius. Unfortunately, the rise of the single and decline of the album have rendered it not as relevant as it might have been.
Live IS completely different. The way I describe the difference is that Sonar is a studio disguised as software, while Live is a musical instrument disguised as software (although now with the Push controller, Ableton is basically saying it is a musical instrument). I don't use Live as a DAW, and I don't play Sonar live as a musical instrument (although I do use it as a host for guitar amp sims).
Then there's Traktor, which is my software of choice for "pure" DJ applications as opposed to the more "DJ-style" use of Live...right tool for the right job, and all that.
All of them had learning curves, with Ableton being the most challenging for me. However, it is internally consistent so once you learn "the Ableton way," it becomes easier. Traktor is very straightforward, but deep. It's easy to get started, but difficult to master.