I have my RC-70's in a room that is a little bigger than yours with a 14 foot vaulted ceiling (bonus room). 20 x 15 with the T.V. / speakers on the wide (20foot) side, open on one side.
The RC70's fill that room very nicely, and get very very loud. The RC-50's would also do the trick actually (I've heard them too and almost bought those, but at the time they weren't on sale and 70's were only $100 more).
Batpigs description of them are bang on. I'll go a bit further though, the RC line really has stunning imaging, it provided almost a 3d type sound field (which is strange for a speaker tha is not an omnipolar design) as comapred to other speakers of similar configuration.
They're also very neutral. I think they're great for just about any application. One person here was once not happy with them though, albeit for home theatre use.
The comments he made was mostly around broken glass. He said when watching a movie and an explosion happens or something else that would cause glass to shatter, he didn't 'feel' it from those (RC) speakers. It didn't sound like breaking glass. I would imagine you'd get that from the Klipsch speakers though, based on their upper sonic characteristics.
That just goes to show you what some people like or don't like about speakers. If you like a fuller, richer, smoother sound, but don't want to lose any detail, the RC line would fit your tastes (as would a lot of other speakers).
If you want something in your face and up front, which a lot of people prefer for strictly movies, then the Klispch would be more to your liking.
Neither is right or wrong as it's personal preference. It sounds like from your post you might be an RC type of guy, but if you can, you should hear both for yourself (get the RC-50's if you can't wait for the 70's) and then let your own ears judge.
Best of luck!
"it's better to have it and not need it than to need it and not have it"