Yeah, this is exactly right. Every person has their role and every role has their person. If you look at the skillset of each class, you find very little overlap with other classes. Building taken out? Demo man or spy. Close range damage? Heavy. Want to make people scatter off that CP or Cart? Pyro. Heavy defense? Engi. It would be frustrating to see the heavy be at 600 HP, because I do enjoy playing sniper. If the sandwich was +100 HP base, you know that EVERYONE would use it, too. The shotgun would be barely missed, but that extra base 100 HP would come into play all the time. Just look at what 75 HP did for pyro.
I think it's more likely that it's not a BASE HP bonus, so when the medic heals it isn't to 600 HP. It may still be capped at 450. That would go in line with what Valve was saying: "Make the heavy viable without a medic, but not overpowered WITH a medic." Or it might just be a portable medpack that he can carry around with him, and hit it once, or once every X seconds/minutes, and get a 100 HP instant heal.
I guess we'll find out Monday or Tuesday. Sadface @ waiting.
