The main goal with using energy weapons is that your ammo supply and power supply are the same thing. You only need to bring along one recharger, instead of a recharger and lots of ammo. For using up battery capacity, that is what the weapon mount batteries are for. You recharge them when you have spare capacity, instead of setting them to auto-charge from your BA's power supply.
Plugging in your Exoskeleton while in the enemy base is considered cheating, and strongly encouraged.
but batteries are FINITE, so you're bringing an additional charger...but now you're taxing it twice as much (or more).
aren't you?
I mean, entropy still exists and there are still only a finite number of hours in the day...
Advantages of ammunition: It 'holds its charge' until you use it.
Disadvantage: once you use it, it's gone.
Advantage of energy: it can charge off the same gear.
Disadvantage: It has to charge off the same gear, leading to a single point of failure for both suits, and weapons.
this might boil down to what your mission actually IS, how often you expect to use your weapons, how often you have to run your suits, how much 'break time' between sorties...and maybe how many power packs or battries you're lugging or how many chargers you happen to have available for your team.
heck, it might even require considering what KIND of chargers you're using (Solar, Kinetic, fusion, fission...) or the duration of your mission/missions. (*in and out quick has different NEEDS than sustained guerilla campaign or LRRP activity.)
how OFTEN do you expect to be in combat? how far are you expecting to travel unsupported? will there even BE time to put everything on the charger, or are you going to have to prioritize?
I think there might actually be a good reason to have a highly modular suit architecture here-there isn't a single weapon good for all the missions a "commando" might be doing, or need to do, so configurable is probably better than "trying to do it all with one type of hardware".