I'm actually surprised by how mature most of the discussion here has been. Most people simply want to delete the class that causes the most problems for their favorite class--never stopping to think that's someone else's favorite class and exists, in part, to help balance their favorite class. Now that's a convoluted sentence, but you get the point.
I play pyro a lot. I don't think they're overpowered or need significant altering. If you haven't played the class a lot, you might be surprised how hard it is to get a good clean kill. Also, they're necessary anti-spies.
I would probably reduce scout damage a bit. They're not supposed to be powerful, just fast. I've found myself playing the class more because I find it can be so easy to crit kill others. I'd consider that a bit unbalancing.
I love Sharpshooter's idea. Flying over the map would be fun, and you'd get mid-air duels. Having to really look up would be a big switch.