I agree about the Songs sub-forum - there's some seriously great talent down there!
I've got a pretty fair track record of albums done in SONAR (either at my own studio or others that run SONAR), and I use SPlat to do all of the mixing and mastering here at my studio. One of these days I'll get together a document with everything in it, but at last guess it was in the dozens of international releases that were done either in part of in full in SONAR.
Not sure if you'd say it's "successfully" because I'm still not a millionaire (HAHA!) but I seem to do OK, and I know some of the artists I've worked with have gone on to have some pretty good success in their own niche markets. And then you have guys like Mr Anderton who make my achievements seem pretty small fry! D'OH! HAHA! But that's what I mean about relative success. It's hard to quantify!
If anyone's interested in a few things I've done in SONAR, a good place to start is with my band LORD I'd say:
www.lord.net.au or
www.youtube.com/lordofficial But yeah, if we can define success as making awesome music with these great tools, there's a LOT of really successful people in these forums!