I have heard that the Trittons are almost exactly the same as the Sharkoons, just a different casing brand etc. And if that is the case then I wouldn't recommend them.
I had a pair of Sharkoons (xtactics or something, around £110) and I couldn't return them fast enough, yeah there was surround sound, but the actual sound quality was horrible. It was like listening to the game through a tin can.
I have gone back to my old setup of just a regular pair of headphones plugged into the back of my tv.
Compared to the sound of the TB PX21, it's HUGE difference in sound quality. The sound stimulated from the 720s sound very sharp, along with the 5.1 surround sound that lives up to its promise.
I own both the PX21 and 720s for a couple of years now, so I know the experience.
i have the ax180's and they are extremely similar to the ax720's. i really like them although the headphone begin to feel uncomftorable after about 3 hours of straight wearing. i would most def pay 110quid