Recently, I've been using headphones only for my mixes and I feel more comfortable with my mixes now, as opposed to using my monitors. I'm in an untreated 1 bedroom apt so the monitors really wouldn't do much good, but I've also taken the time to really get a feel for my headphones. I also do playback on 4-5 different systems to see what jumps out at me mix-wise. To each his own, I guess.
If and when I upgrade to a true studio environment, I'll bring back the monitors and use the headphones along with them