Originally Posted by
Nocturnis
Siegecrafter : Combat all the way. Having those cd up everytime means you are a solid dps there and allows your guild to assign even less people on belt duty.
Paragons : As stated there is so much movement and things like that that sub just isn't viable. Combat is ok but cleave is useless, i wouls say assa is best here
Garrosh : I only did it as sub for the engineers and i can't complain about boss dmg or anything so i really recommend sub here
Also for your initial question about gemming. Atm i am running sub gemming/reforge even when going combat and the difference is not there or is very little. My haste went down from 18k to about 15k and the impact on my gameplay is nothing. You will have less haste and so less uptime on cd but that extra agi will kick in.
Edit : i also run with a sword/dagger in combat and just swap them around for sub. For me this is the best thing you will get so that you don't have to change so much between specs.