I jumped to Cubase and finding there are a lot of pluses to doing so. Sonar is easier to set up screens and record midi/audio, so composing for me is just easier/better in Sonar. But after that, Cubase just is head shoulders more advanced especially if you score to picture. Latency is not an issue, Notation is way farther ahead, you can move video around, Cubase's version or ProChannel opens all the channels at once (not just the one channel), tempo is handled much better and Variaudio is like having an advanced version of Melodyne and Audio Snap all rolled into one (the only drawback is no polyphonic auto tuning).
After what Gibson did and seeing all the better features in Cubase I am kicking myself for being such a Sonar "fanboy". I Should have jumped ship long ago.