I was doing Drak'Thraron, Gundrak, and UT Keep in a lot lower gear and under hit cap (like 50 hit and around 2k SP before TOW). Granted, there are some fights that were very close calls almost all the time. Trollgore was one of them. I since started farming badges for my 4 pally / DK team (haha - i'm such a bandwagoner) and this was when I really noticed a huge difference from before, so I decided to step it up and try some of the other heroics.

The biggest things that helped me is to 1) have hot keys to have everybody heal an individual toon, so that as one guy is getting burnt down, they all stopcasting, and immediately heal him. 2) Keys (such as arrow keys) that move your entire group, so for fights that you have to move quickly you can move. Drak'Tharon and the soul mages come to mind.

Another thing is that if you are close, but just can't quite squeak it, you can use drums of forgotten kings, drums of the wild, scroll of fortitude, food buffs etc. to buff your entire team. You can tell from some of the screenshots where I was using some buffs and no buffs. The difference I'm seeing is nearly 4k HP -- 27.4k buffed, vs 23.6k without them.