Probably not a good idea. Your ears are incased in little boxes (ie the cans) so its not really a true representation of what it sounds like in a room.
Also the shape of everyones ears is pretty unique. So basically you will be mixing to fit the exact needs of your specific ears, being that the sound is being pummelled straight into them. And this won't translate too well. Its also pretty much a fact that if you mix in headphones, and then go to see how it translates on a completely other system, it will be dead off.
I did a few headphone mixes on some of my stuff ages ago and in every case, there was not enough low end. Headphones tend to boost lows a bit. They tend to color the sound you are hearing an awful lot, and kind of make it prettier. Which is great if you are just listening to music, but you don't want it to be made pretty, you want it to sound as it is.
The way I see it, if music is to played on loudspeakers, then it needs to be mixed on loudspeakers. If your mix sounds good on any set of speakers, then you can guarantee it will sound good through headphones also.
Also spending hours on end listening through headphones all the time will cock your ears right up.
I generally use headphones for like checking for bleed, noise, crackles and any imperfections in the audio that might need fixing. They are good for precise listening in the sense that you can pick stuff out easier, but they won't really help too much in mixing IMHO.
