I am using A 500Pro since my 8.5.3 and x1 days. It has been very easy. Installed the driver, connect the USB cable, press the ACT button and some simple setup at X2 and you are all set to go. I used the tranport button the most, record, play and pause, then the knobs and fader. It's advantage is it is designed to work with Sonar from the start. It can instantly swtiched to control any synths or effects plugin or the mixer volume and pan, depand on which one is being highlighted.
It comes in 3 sizes, A300pro is 2 octaves, A500pro 4 octaves and A800pro is 5 octaves. BTW I am not a Cakewalk salesperson.