SFX pitch would be an interesting adjustment, even better with increased SFX speed as well, though this wouldn't be a simple toggle so it's a bit much work for a single utility effect. All the sounds would have to be checked for what pitch and speed adjustments work right for them.
But that's the least important issue--animation speeds can't be adjusted like that due to how particles are created. These (and related timings!) would need to be adjusted for every particle involved because otherwise the appearance could look quite different.
I mean, overall it'd be a really fun experiment, but there are too many applicable weapons to do this for xD