I've had a chance to play several rounds with the APC, both as crew and non-crew. I thought I'd give some thoughts on it.
Feedback:
As anything other than a support vehicle, this thing massively under-performs. Right now everyone from PFC to the actual crew quite commonly make the mistake of assuming it can lead a charge. It can't, it can barely defend itself. Honestly a single lurker could probably destroy it without much trouble. On a larger map it might be able to flee.
This is, with some balance issues, mostly fine. It could do with some IFF capabilities, especially since its guns don't do much.
Driving is a bit janky, mostly the same issues as the tank. The speed is a problem in most cases, as there's rarely a long, 3 wide corridor to drive down. Haven't had a chance to see it on Corsat, and when I watched it on Trijent marines were immediately penned into the LZ2 area. I'm sure on these two maps it'll perform better.
Driving into plasteel cades counts as a "crash" as far as the occupants are concerned. Maybe this is intended behavior.
The lack of external sound is a major hindrance to the crew, and also kind of unsettling.
You can't tell how damaged it is without getting out, which is a little annoying. Also sometimes movement is arrested for unknown reasons?
Nearby marines don't benefit from Issue Order, which seems like a benefit that's very desirable for a support vehicle (especially if you took the command one).
Needs some sort of zoom function for Driver/Gunner. Without sound, you're basically driving around blind and deaf. Suggestions on gitlab already asking for a tac-binoc function for the command version.
Suggestions for Marine Strategies:
Standard Module:
I think the max occupancy is 8, including crew. So you at best have a 6 man team. You can load crates inside, tried to see if Icould load a sentry/mortar in but crew weren't interested in testing that. 100 Sandbags + Sentry + a couple engineers and a Smartgunner and you could have a nearly instantly deployed position. I think this would be good for Containers/TFort on LV, Near Chapel on Big red. Also, a crack squad could use this to rapid flank on maps that encourage flanking and also have a 3 wide-corridor.
Command Module:
You have an overwatch console, and hopefully an SO volunteers to man it. Your max occupancy is reduced (I thnk). Many people so far consider this setup to be the worst option, and I have to agree. A really coordinated Command team might be able to pull off something, but this thing doesn't even have a radio inside, so if you lose comms, the LT might as well be outside giving orders. Honestly I'm not sure what the strat would be here. Dev Suggestion: Have the SO be in the APC the same way the TCs are in the tank.
Medical Module:
This has been the most common variant chosen so far. Field surgery is very nice to have. Crew MUST lock the APC doors if they take this. Every wounded marine in a 10 tile radius will attempt to enter. All to often I see the crew getting bored and driving to the front in this model, despite having a doctor (or synth) inside. In my opinion, if this variant is chosen, command would do well to order a field hospital to be setup somewhere that current meta wouldn't normally consider for a full base. E.G. Set up at Tfort if caves being pushed, set up at junction north of Engineering annex. Some sandbags, a turret, and medics could be pretty comfortable treating wounded.
I haven't seen an APC win for the marines in the same way as the Tank can. Guns are far too weak to do damage to crusher/queen. It could MAYBE take out a prae that was stupidly overconfident and alone. The key to using it effectively is going to require coordination across multiple departments or squads. Personally, I love the thing. Never been interested in the tank, either you have things to shoot at, or you're waiting to have things to shoot at. The capacity for unique strategies and divergent gameplay makes the APC an excellent addition to CM, but the high skill cap and need for marine support is going to quickly give it a reputation as hot garbage. Also, can't really compete with an LTB.