I've gotten quite a few comms on all of my dps classes (as well as my healers and tanks). I can't say for sure how many are from what classes now but I had around 200 comms by the time I reached lvl 60 on my bard. But I mean I've had people give comms for being helpful, listening to advice, giving advice, just being friendly, and even things as simple as liking my glamour or thinking my toon was cute. So I mean I can't chalk up the comms I got to class or how I played that class.