I'm having the exact same troubles as you, Kurugi. Having run through a lot of the available classes and deleted them again, my first real toon is a DS op (lvl 24) and a LS sorc (lvl 28) - both healers, since that's what I always play.
As for the overall experience, I agree with you story-wise. The IA story is great, yes, but you kinda feel like a roadie. Getting involved in the inner workings of the sith is really where it's at - where the whole SW thing is. You're greeted on new planets by people who've heard of you, and who's been excited/scared that you're coming. You're somebody special. As an IA, you're the puff of smoke coming from the grassy knoll. As a sorc you're accompanied by a legendary assassin, who's always threatening to devour people. As IA you're accompanied by a freak show with a yellow hardhat (oaky, I bought it for her I know).
This is reflected in the aesthetics as well. My sorc's robes are beautiful and she spews lightning from her fingertips. My op wears a grey raincoat, a blue baseball cap and is just ... grey.
Healing as a sorc feels incredibly WoW-priesty. Very, very familiar. Mana ... sorry ... force issues seem non-existent really. You're only really challenged by the erratic behaviour of pugs (let's attack three different mobs simultaneously!). I get banged up badly in PvP. Also very WoW-like As the other poster said, op feels new and fresh .Sadly it's also a new mechanic my old brain needs to wrap around. It's great to think you can heal forever, but burst periods are just angst-filled. PvP'er is funner as op. Even as the worst PvP'er ever, I top healing meters in WZs and I even get a few backstabs and shivs in (followed by instant death but totally worth it!).
My sorc's on Tattoine now and it blows more than sand! Op's starting Nar Shadaa, which feels like a differently lighted Curoscant. I'm a little fed up with questing atm. I have a lvl 11 commando healer, but the whole military thing does nothing for me. My solution now - because I do genuinely love this game and I haven't had this much fun since running my priest through Northrend - is to PvP on the Op and do Heroics and FPs on the sorc.
Let me know what you decide and gl with it.
Cheers!