Please, never change the movement.
As someone who grew up playing games like Quake 3 and Quake Live, nothing keeps me more entertained in a game over the long-term than good movement.
Don't get me wrong, I like the meta progression that's in place in the game but something just tickles my brain about a movement system that you have to learn and master, like the ones in Titanfall, Quake, Krunker, games like that.
There's just something so satisfying about getting the timing down and seeing a progression of your skill that actually has benefits in the game. Do I think they should balance around that? Not really. Not everyone is going to take the time and energy to learn the movement, so I wouldn't want players having to learn something they're not interested in to do really difficult missions.
Although, skill in the movement system would help you out greatly in the higher difficulties, because the fewer enemies that are hitting you, the longer you're gonna last.
Edit: Made a short video here that half-ass explains how to do the movement tech!