My experience with headsets goes from the low end to the high end in the past 24months.
I started off with the Steelseries Siberia's These for the price are really good for playback. Not overly comfortable IMO though and the mic is really poor, with it being a clip on. It can take a while to set-up in TS/Vent/mumble till your happy with it.
After the steelseries, I went onto the Razer Carcharias. Miles apart from the SS an they should be given that they are nearly double in price. But they didn't last that long. After roughly 8 months of good solid gaming the left speaker cone started to go and on bassy impacts I could hear it vibrating. It seems this is a common trait with them and something I didn't see first of all when researching them. Whilst they worked though, they were really good. Could hear the sounds in various directions well, and gave a good advantage in FPS games.
Last september time, I went for the Sennheiser G4ME 360's. These were fresh on the market at the time and are openbacks. They have completely changed the way I hear things. I even listen to my music through them over my free standing speakers that I have. The openback does take some getting used too, as you do hear the background sounds around you, but once you have learnt to shut them out, my god! These just blow you away. Everything is crystal clear, really comfortable once broken in. They completely seal your ears for maximum sound. The boommic turns off when you push it up out the way. So no need to have a bind to turn the mic off. Volume control built into the right speaker, so no extra weight on the cord. If it wasn't for the mic being on them, I'd happily use them with my MP3 player too.
One other thing I'd like to add is, without a good soundcard, your not going to get the best out of your headset. I ran all 3 of those headsets through the Creativelabs Xtremegamer card which seriously helps with how you hear things. I say it everytime I talk to people in my clan, the single best upgrade I did was get that soundcard. 2 other people in my clan now have it, after hearing me banging on about it. They now understand why I go on about it, whentalking about upgrades.
