Which model of the Icons were you looking at? I can't speak authoritatively on the nuances of speaker matching to room size, there are folks here far more knowledgable than I on that. But, I do have a set of Klipsch RS-41 rear surrounds that work very well with the rest of the group, which is the Atlantic Technology 4400 series and 642e subwoofer. I've read that some folks find Klipsch's on the "brassy" side, due to the horn tweeter construction, but, like anything, it's a matter of personal preference. You want to make sure that they can be driven safely by your AVR or Pre/Pro at the levels you wish without clipping or distortion, but the best bet is to listen to (like you said) speakers in environments close to what you might be hearing in your own room. Also, of course, budget is a major consideration! I listened to quite a few speakers, not knowing anything about the higher quality sound from better built ones, but I took some material I was familiar with (Iron Man bluray) so I could compare more accurately. Also, room correction and other factors from your sources will alter the sound, sometimes greatly. Check out reviews from various sites such as this one, or Hometheater.com, HomeTheaterShack.com, etc. which helps you see where you might consider . Keep in mind placement will be very important, since you will need to build for that. Since you're going with an AT screen, floor standing models can work, though you may have to elevate those, too, to get them to face the audience correctly.
Better to have a little headroom and have a little more than you need than come up short wishing you went with that next step up! the speakers, projector and AV equipment were almost half my upstairs budget! And I still got a pretty good deal, I think!