I'm another who prefers to have two Medics on hand at all times. With just one you can't guarantee they'll be in range of wounded units you need to heal. With two it's much easier to manage. And in larger missions, such as the base assault or the final mission, you might well need those six med-pack uses instead of three. Plus it's not like supports are slouches in the damage department either - laser and plasma rifles do just fine.

I tended to go two Supports, one Sniper, and split the remaining slots 2/1 between Heavies and Assaults (I changed up which between files). Yeah, Snipers are amazing, but I never felt having only one hurt me. Of course, I never played on Insanity, either, so there's that. Did play on Classic and did well, however.

I also tend to grab Carapace Armor before Laser weapons, albeit mostly because I tend to unlock it first. Both are an important investment though, so in the end I don't think it makes a huge difference which you grab first, so long as you get them as fast as you can.