@totolecc Huh, I've played both and they're nothing alike, I assure you. If anything it could remind you a bit of 8 due to the use of the same engine. For me is plenty good, one of the few MM where the powers you get feel earned.
Both MM&Bass and MM IV for Game Boy make a good use of the shop, by the way (the shop started with that GB game, in fact). I recommend you both.
Oh, one more thing, have you played MM10 with Proto Man? I feel like that game's more fitted to that character more than the MC, funnily enough. With Bass is cool, too, and the hard difficulty setting makes the robot masters make an extra movement. And other changes through the levels.