I'm still using Sonar 3, for much the same reasons you just cited. But when v.8 came out, the magazine critics raved about how superior it had become and especially some new MIDI editing tools that they said made work far more efficient. THAT, immediately got my attention.
Since I primarily use Sonar for MIDI, that has/had great appeal to me. I'm also starting to get my toes wet with using software synthesizers, and I can see that this could become a lot of fun for me.
There's one primary obstacle holding me back. My computer. My 2004 machine now qualifies for the bare minimum requirement to run Sonar X1. When I get a new computer, then I'll upgrade Sonar, too.