Hasbro answered a question for me back a while about the "look" of the line... I asked it because there was some doubt on a rumor report I had posted prior to Toy Fair '08 where I had it from a good source of mine on the style these figures were going to be and whatnot. And that they were going to be sculpted halfway between realistic and animated rather than completely one way or the other... Hasbro wound up showing all 3 styles, which they'd submitted to LFL, of Anakin. It was really quite interesting to see a completely animated, completely realistic, and the hybrid of the two Anakin we ultimately got.
Anyway, that said, I don't see a very realistic look to any of them save for the droids... And they look like just different variant models of droids more than say 4-A7 looking like an RA-7 type droid at all. I got 4A-7 because he just looked like some kind of variant prototcol droid... That worked for me. Same with IG-86 and I think I can live with Commando Droids as they are...
Not many of the human or alien characters look realistic at all to me though. Ahsoka, sort of, but not quite really. It's a big reason I don't even pick any of them up to try customizing them to a more realistic look. If any organic character "fits", to me anyway, it's Assajj... She's not terribly different from her realistic sculpts and really I find her a better figure overall than her realistic counterparts in one way or another.
Captain Argyus, who I've not seen in person yet, might work with a different headsculpt attached to the body. The armor helps in ways that are similar to the way droids can pass as realistic. It just looks like a different type of armor... I wouldn't try mixing a phase 2 realistic Clone with a CW3D Clone and calling them the same armor, if that makes sense. Argyus really doesn't have much in the realistic line to be compared to though, save for the Senate Guard figure. One could always just say he's a Captain of the guard so his armor's unique (like a CLone Commander's). Replacing that headsculpt would be tricky though, but there's a ton of generic heads floating around out there too, so it's not impossible.
EDIT:
By the way, I'd consider a repaint of some of Ahsoka's finer features, namely her eyes, to try and make her figure fit in better. I'm not sure if replacing her arms or something might help. I got Ahsoka for the baby Hutt and pack at the time on sale, but I can't find the Ahsoka figure now to really comment from a customizing aspect much. Paint may help her blend in a little better though, IMO.