I made a game that didn't use custom movements.. then it came and bit me in the arse 2 months later Ironically, Construct did that engine perfectly well with built-in movement, but buggered up the sprite clones.
Oh, there's a bunch of extensions that make the game work as well as most custom engines without the annoying hassle of 2-4 detectors per sprite. Lol, Nash, hurry up and make a game. I liked the turn-based fighting dungeon crawler thingy you made before. I'm pretty sure MMF2 could handle that now.
Disclaimer: Any sarcasm in my posts will not be mentioned as that would ruin the purpose. It is assumed that the reader is intelligent enough to tell the difference between what is sarcasm and what is not.
The PMO is pretty genius, saves you doing all the fastloop stuff, messing about with detectors and makes it easy to attach animations to movements. Unless you plan to do something very unusual, the PMO can handle all the movements you could need (wall jump, swimming, flying, low grav, springs etc).
The only time where I wouldn't use it for a platformer is in a Sonic-like game with complicated physics, but then again I'd never make one of them anyway.