Yeah, having a good squad makes a world of difference. I've been playing alot with my buds from AVS, typically we win around 80% of the games we play in when we play as a group. Had my best round ever when I choose enginner and hopped in as the gunner for a tank driver, ended up 25-2. I didn't get out of the tank until we'd blown up the second set of M-Coms, and that was only to repair (unfortunately I didn't see that sniper oh so far off who trimmed my hair about 6 inches). But it was ridiculous, we absolutely steamrolled them, when we destroyed the final 2 M-Coms we still had 65 reinforcements left.
I've tried both the armor and the magnum rounds, honestly I can't tell the difference when using either. By the numbers for most guns the armor should be better but I didn't seem to survive any more than I typically did.