I'm not entirely sure how you could find an RCS holster "big and bulky." It's one of the thinnest Kydex holsters I've seen, and they're certainly much slimmer than any leather holster. The thing I really like about mine is that the position is just absolutely perfect. Other than the fact that the gun adds a couple of pounds of metal and plastic to my right hip and the IWB model makes my pants just a bit snugger, I really don't notice it that much (and *that* is from someone who only wears her firearm on special occasions like training classes and group meets) -- and those two points are all gun, not holster.
A couple of other nice points:
1) the eyelets go all the way down the sides of the holsters, so you can adjust the loops or attachments to be in almost any position you like, as well as giving you the capability to add on other pieces like legos (such as putting two mag carriers side by side, for example).
2) The Kydex is very smooth, making for comfort against the skin, limited snagging of clothes, and a quick and silent drawstroke.
Yes, I've totally drank the kool-aid.
Here's a couple of photos of mine with the flexible loops for IWB for my Sig P250, with a decent shot of the back of it.
PS, I will also add that while W9ZEB admits that the Raven holster is very comfortable and he doesn't mind wearing it, he does like his M-tac because the leather back conforms better to his hip than the Kydex of the Raven does.