An enjoyable walk-through to better understanding! Many thanks, IBPH!The difference between thin, medium and heavy shells are pretty subtle, but still worth caring about for 'people like us.' haha
Here are the differences as I understand them: (feel free to correct me if I'm wrong)
[All these differences are slight, they aren't night and day]
Thin: lower fundamental note, more resonance, less projection
Heavy: higher fundamental note, less resonance, more projection
Thin is great for lighter styles, vintage styles, but doesn't cut quite as much. It doesn't take as much effort to excite the shells.
Medium is the best of both worlds.
Heavy is great for louder music where projection is necessary. It takes slightly more effort to excite the shells.
If you want more cut or bite or presence from, say, your bass drum.....make it a thicker shell. If you're more about nuance and delicate playing, choose a thinner shell.
All that being said, if for example you choose Heavy shells, they'll still sound great on a jazz gig.....and Thin shells will sound great at a rock gig. It won't be a huge difference one way or the other.