Honestly I feel like the multicannon's alt fire modes are a bit out of place. It effectively has 3 alt modes: swap, zoom, and overheat. I could be wrong, but it feels almost like the zoom is a bit overpowered simply because it allows it to be extremely versatile at literally any range. With such a limited amount of weapons, this makes it very important in most loadouts. That being said, you would definitely need some other weapon with zoom to take its place and be an actual sniper, instead. Of course down the line you could make weapons that are more powerful at long ranges or just as capable at even longer ranges, but right now it just feels that the one weapon capable of the longest range shouldn't also be just as powerful at all the other ranges in between.
This is sort of a continuation to be my thread about bindings, because in order to ado a way to swap modes that isn't awkward for scrollwheel users, you'd have to either make a whole new button or get rid of the multicannon's current at fire. I'm suggesting the latter, as it would be a way to implement a better swap buttons, as well as (in my opinion) a balance nerf to the versatility (not the actual damage) of easily the most versatile weapons right now.