I've converted a couple of Sonar projects over to Studio One and, so far, I really like working in it. I've had zero issues and their midi implementation is actually way better than the rumors suggest. I'd say if you work in the box and don't need advanced midi stuff like note expressions (in Cubase), you'll be fine. However, if you use hardware synths and like how Sonar can show patch names and basically integrate with external hardware, Cubase is likely the better solution.
None of that is available in Studio One. You can still sync external synths, but all patch management has to be done on the synth itself. Also, I'm pretty sure you can't sync S1 to an external synth, though you can sync the synth to S1, if that makes sense.
Regards,
Dan