It really depends on what kind of feedback you want. Do you want someone with a more hands on approach that actually moves you to correct positions or would you rather have someone who primarily uses video. Personally I think the best teachers (those that you will find the most long lasting consistant results) or the ones who use a more hands on approach and may lightly supplement video as well.
Hulk: If you have very handsy swing and still generate a lot of distance than you probably won't really sacrifice much distance even if you attemp a major swing overhaul. Look at the professionals that aren't big but hit it extremely long and how much they use wrist angle and hand speed to generate club head speed. (Sergio, Michelle Wie, Charles Howell, etc.).
I know the two pros at Kenwood have a teching philosophy in which they don't try to make you swing like anyone else (many teachers try to emulate certain pro's swings) but lay down the fundamentals and can show you how to get better within your own swing. I would expect them to be more expensive when compared to some of the other pros in town considering of where they works.
Hope this helps