Great! I'm cooking up a suit class system already.
Guns will take up hardpoint slots, heavier guns = more points taken up.
Heavy Class - 15-20 hardpoints.
Medium Class - 10-15 Hardpoints.
Light Class- 5- 10
Scout Class 2 - 5 hardpoints.
Scouts make up for lack of hardpoints for being smaller and faster. However, due to their lighter body types, they can't take much damage.
Light Classes are great for rushing, not for extended firefights.
Medium Classes are standard soldier style suits. Great for combat, but kinda slow.
Heavy Classes are made for laying waste to whatever area they're currently in. Because of their heavier weight, they can take enormous amounts of damage, but are extremely slow.
There are rare custom Super Heavy types, but you'd have to have some form of license to pilot one (I.E. GM would have to okay it, and not everyone gets one.)
If you disagree with this system, make adjustments as you see fit.
As for miscellaneous weapons, I'd be willing to accept things that essentially break physics. An example would be Lost Planet 2's Black Hole Martyr System.
Just an afterthought, what about wearable suits, kinda like VANQUISH, or TITANFALL? I mean, they'd be more like infantry, and be able to hit other suits where they'd be vulnerable, such as exhaust ports and joints.
Again, if you disagree with anything stated above, please fix it as you see fit.