Quoted from shaub:"likely correct," I'll take it! haha
Frankly, I'm glad they don't stack because that would even further benefit you for playing as Raph and as it is, I really wish the Turtles were better balanced. It's a cool, unique-ish feature of the game but it is underdeveloped/unbalanced as it currently sits.
I totally agree, all of Raphs perks are pretty useful for scoring big. Some of the other turtles perks are pretty underwhelming when compared. Especially the perk for 2x team up multiball. That one in particular seems very weak considering how little you play teamup, and the fact that you could easily reach that level after playing teamup the first time, and getting to it again isn’t easy at all. And 2x pizza eating contest is only an extra 2m points or so here or there since pizza eating doesn’t come up too often either. Also I kinda wish there was more incentive to level up at all. The flat 10% bonus scoring per level is nice, but even though cowabunga is hard enough as is, I feel like getting to level 3 or even 4 should be a requirement to motivate us to level up. The neutrino pizza party mode is pretty lackluster and I rarely try and play it.