I actually have both the Studio and the Pro version and I have to say the Pros give a much crisper and clean sound. Over all performance is flat out better and with the aluminum frame and parts they are pretty bullet proof other than one thing I did find frustrating. If you choose to take off the ear cushions or pop one off accidentally they are one real pain to secure back on. I probably sat there for a solid 30 minutes trying different techniques before I got all the inner latches to click in place. I will admit there is probably a proper technique to this. I do like the option of being able to use the input port on either the left of right ear piece and really like the fact they don't take batteries. I can't even count the times I have put away my Studios with he power on to find them dead the next time (really a pain when on a long flight or trip).
There are two HUGE advantages the Studios DO have over the Pros and here they are. 1) The Studios are significantly lighter than the Pros . The Pros are actually so heavy that I can only take 30 min of them before I have to adjust the head piece to another spot on my head which usually compromises the ear cup seal a bit . 2) The Studio's noise canceling feature is very advantages when on a place or another setting where you really want to take yourself "away" a bit.
All and all they both have their pros and cons but considering the Pros are $100 more and have the weight problem I would definitely recommend the Studios.