I couldn't possibly imagine using anything other than studio monitors. I'm too used to the accuracy they provide.
But I know that some people are actually able to make some damn good tunes using headphones. Ian Lehman for an example, he has been only using headphones to make his tracks. I don't know how the hell he manages to get such a great sound when only using headphones, but he does it!
Personally I don't think he's human :lol: