All arguable points. It really is a matter of your group makeup. I was in an AOE happy LH group last night and the reaver build allowed me to maintain aggro on all mobs most of the time, there were a few not so good moments. I'm thinking I will keep two tanking builds up for myself. One for heavy CC/single target groups in later dungeons and a second for AOE groups.
Also, people seriously need to learn how to assist in this game... For the record.. It's the F key, or better yet /assist macro.
Another note: I am quickly noticing the good players from the bad. I gave another tank the opportunity to tank through LH a few times while I switched to DPS. He was bad, I mean real bad. Managed to get us killed several times. As soon as I switched to tank it was all good. I am by no means saying I'm amazing at this game but I feel I'm better then most people I have run into...
And so naturally you made an effort to help this other player be a better tank right?
I think you'll find this sort of thing happens when people switch to their off-spec role. It's difficult to learn how to do a thing without doing it a lot and tanking is no exception, it's really nothing like dps and the same rules don't apply.
I remember the other day I tanked LH normal, it was the first thing I'd ever tanked.... ever, despite keeping the gear on me and keeping the spec up to date in points and ranks, I'd never actually used it. For the first couple of pulls I sucked, hard, and then I figured out what I was doing wrong and we finished the instance with no other problems, but right at the beginning there I didn't have a clue beyond reading tooltips and trying to reason out what went where.
My point is, when you "let someone else tank" when they're normally a dps, you should expect it to be a bit rough while they figure out what to do, or you can help them by giving them advice, or you can come to a forum and proclaim about how you're a far superior player on your main spec than this guy is on his off-spec