Good idea for a post, EA_Rtas. I especially enjoyed the pun 😄
Here's my feedback, but I should mention it's mostly from a Breakthrough POV.
Balance
How does the M1A2 SEPv3 feel right now in actual matches?
I think it works very well if you play in a similar way to BFV - support infantry from a slight distance and move up with them. Trying to rush a point solo does usually result in me getting blown up.
Does it feel too strong in open areas, or too vulnerable up close?
It definitely feels better in open areas than up close. It'll still work close up, but you'll probably need to rely on the secondary weapon and have to work a bit harder.
Loadouts
What’s your go-to setup and why?
If memory serves I've got the default "big gun" set, guided shells, the LMG as a secondary, thermal smoke, and the mine clearing tool. I mostly use this as the primary weapon options work well for enemy vehicles (especially the guided shells), the LMG melts infantry, and the other stuff, in theory, keeps me alive a bit longer.
Any attachments or upgrades that feel mandatory or completely useless?
I think something to deal with enemy projectiles is a must. I personally prefer the thermal smoke as it gives any nearby friendly soldiers some cover, and gives me a chance to retreat.
Playstyle & Tips
What separates a good tank player from a great one with the M1A2?
Reading their team well. If they're not pushing then it's probably not the best idea to go it alone, and if they're fighting hard for a point, don't hang back near the uncap lobbing shells at random.
Best positioning or tactics that consistently work for you?
I already touched on this above, but I try to stick with my team wherever possible. I do try to avoid putting myself in situations where the enemy can easily hit me from above too.
Counterplay
What’s the most effective way you’ve found to deal with this tank?
Rockets!
In all seriousness, I find that the RPG works best for me. There's no lock required, so it doesn't warn a driver, and it reloads pretty quickly. I usually try repositioning after each hit, but sometimes just try putting as many rockets down range as I can and hoping they're busy killing someone else. It also works pretty well at both range and up close, so sometimes try to hip-fire tanks.
My favourite way of dealing with them, though, is with the repair tool. Always puts a smile on my face.
Does it have any clear weaknesses that aren’t being used often enough?
I see a lot of people attacking from the front, and while sometimes that's the only option, it's much better if you can get behind the tank.
Also, most people seem to choose the regular mines, but the SLAMs are what I use myself over them usually. They're really handy for creating traps as you can stick them in odd places where drivers don't always check, like halfway up a lamp post.
Hot Take
What’s ONE change this tank needs right now?
Tough question. I'd probably increase the turret speed ever so slightly. Sometimes it feels a tiny bit too slow.