Ive never had any problems regarding comfort. Other headsets I've used always made me feel like there was a lot of pressure on my head, but this one does not. And the microphone is great. I don't use teamspeak, what I do sometimes is play games with my friends while talking with them on skype and my main friend immediately noticed that I had a new headset because of the quality of the sound.
Is is better than the Siberia V2? You be the judge, right now in Amazon the 780 is at $57 and the Siberia v2 is $90. In the reviews they bith have 4.3/5 which is really outstanding. I recommend you read some reviews and decide on your self which is better. Also go and see unboxings and reviews of both on youtube, that might help you make the decision.
Razer Tiamat 2.2. Are right at the $100 range. Has 2 drivers on each side of the headphone one dedicated to the lows on each side. Pretty good sound for a gaming headset. Works well with gaming and listening to music. (As long as you not a big audiofile)
BTW if you are using onboard sound you might not notice too much of a difference. Even the $30 xonar DG is a good small upgrade just for the options it gives you(i.e. Dolby headphone, better equalizer). Just something to think about.