Originally Posted by
Treeba
There is no cost to respec for subs, but there may be for F2P. You can unlock field respec in your legacy, but it's not true dual spec. It's better in that you can spec whatever you want whenever you want, but worse in that you need to redo your keybindings each time. Fortunately there are usually only a few ability changes between specs.
You can respec and everything is fine. It's just like WoW. You don't need to level as a tank to tank at end game, but you will need to spec Immortal to tank FPs at max level. Tanking as veng for lowbie stuff is possible, but it's ultimately going to depend on your healer. I've run into very few pug healers I trust in SWTOR, so try it at your own risk.
I actually recently leveled my guardian (jugg) as tank from 26-41. It's pretty quick. Immortal tanks get a lot of decent dps talents low in the tree and at 26 Crushing Blow will really let you plow through groups of mobs. I found once I hit ~41 it was faster to level as Rage, but Immortal is still more than viable. If you want to level as a tank do it. It's pretty quick until probably 45+.
Rage is on the weak end for end-game play, but it's more than fine for leveling. The auto-crits on smash/raging burst make it quite effective at bursting down weak packs of mobs quickly. I wouldn't bother with veng until you're 57. At 57 you really need to go vengeance. Just use vengeful slam once and you'll understand.