^ I would switch to combat for a few fights too but the stat priorities screws it for me. I don't want to have to reforge - and obviously not going to get a 2nd set of gear just for dmg meters. The sinister strike ship sailed for me a long time ago... was combat for the longest time and got bored.
Grats on the legendaries btw. I am at 38/60 cause I've had to miss a few 2nd nights... we would obviously clear in 1 night if we weren't so hell-bent on some heroic attempts... but I also understand the other raiders are bored with just clearing regular. I'm just afraid there'd be no more raids to get gems after Diablo 3 comes out in a few weeks.
I guess it doesn't bother me as much, because I've been mostly playing as Assassination spec since Vaelastrasz the Corrupt in Blackwing Lair. Although, I don't think Combat is any less interesting than Assassination, but it is kind of annoying at times.
I run into a bit of a quandry at times with it. I have 3 combo points, hit Sinister Strike like a good little boy, Sinister Strike crits, the glyph procs, and I gain 2 combo points. So, now I've got 5 combo points and no Revealing Strike debuff on the boss.

It makes me wonder if I should try and use Revealing Strike
earlier in the combo point generation to ensure it is up.
The one thing that I like is that if I'm an idiot and I use Revealing Strike when I should use Slice and Dice with my combo points, I can still use Slice and Dice, but my next combo point generation will just be using all Sinister Strikes since the debuff will still be there (15 second duration I think).
Yeah, I used to use Combat without switching stat priorities as well, and it's definitely not
as good, but it's not that bad either. I would still lead on the damage meters, but obviously not as much as I would the other way. The only difference that I see is that you swap mastery and haste around in their priority. I still have 17% spell hit.
I know what you mean about being hell-bent on clearing heroics. We're working on spine right now, which is definitely not that pretty! We've had a few points where we don't get enough DPS on the tendon to kill it in two intervals. As Combat or Assassination, I can get a cooldown (Adrenaline Rush or Vendetta respectively) for each tendon DPS phase, but I don't think that's the case for every class. I usually end up neck-and-neck with the Feral Druid when it comes to damage dealt to tendons, but everyone else is usually 500k-800k behind.