I understand Shadows are generally considered one of the weakest DPS classes. But is that the case only for late-game Ops, or are other classes like the Sentinel stronger throughout the whole game? I mean, when my girlfriend and I are doing heroics/Flashpoints at level 20, 30, 40, etc am I gonna be more helpful for our group as a Sentinel, or it doesn't really matter? Also, she'll be a healer Scoundrel if that matters at all.

I've come back after a really long time. Last I played the commendations were planet-specific (you had Tython comms, then Coruscant comms, and so on). Anyway, are there specific planets that I should save my comms for? Like if for some reason Tatooine items are good or something, I don't know. I'm only level 10 and I already have 12 planetary comms. Also, what items are worth buying with comms? Lightsabers? Robes? Pants? Mods? Or do I just have it completely wrong and should be doing something else with them instead?

I understand they're generally considered weaker than other DPS classes. But is that the case only for late-game Ops, or are other classes stronger for pre-55 Heroic/FPs as well (i.e. are they weak throughout the whole game)?