IMO Tactics REQUIRES a medic. I bumped Stitch upt to 100+ each quickly but as they were tagged that wasn't hard. With the requesite kit, First Aid was as good or better than Stims and the only drawback would be the eventual "Bandaged" condition, which can easily be fixed with one 'Doctor'in round.
In Tactics, with the INSANE amount of loot it helps to not have to carry a bunch of stims, especially since my main got shot up frequently.
I don't use First Aid or Doctor much in the RPG-Fallouts because (at least in F1, just started F2) Stims "grew on trees and fell from the sky," as the bible describes ammo availability. I never got chem addicted and I'd pop em frequently. I assume the First Aid kit would make the skill much more effective because admittedly the skill heals a pittance without it.
They have their bonuses, but other than tagged skills and lockpick none of my skills ever really go above the 30-40 range.