BerserkBeagle:Thanks for the response Jason. A few more questions...
Do you know the recommended height for the 6LCRs?
Can bookshelf speakers be laid on their side? I have AV racks on either side of the TV that would put 6Bs/5Bs at the perfect height, but the space between the shelves isn't high enough for the speakers to stand upright.
Finally, how important is it to have your speakers match. Will I get better performance out of the system as a whole if my center channel and rear ceiling speakers are also Aperion?
At some point in my life I knew a Jason Hicks and it is driving me crazy as I am trying to place the name. 
For the front channels ear level is recommended, so around 3-4 feet. But 5 feet isn't too much above ideal and you can aim the tweeters down to your listening position.
You can lay the speakers on their sides but it will mess a bit with their imaging, that is where you hear sounds coming from especially when things are panning back and forth between the two channels. If it's an enclosed cabinet then I don't recommend the 6Bs as they are a pretty bassy speaker with a large back port so putting them in a cabinet is a recipe for them to sound fairly muddy. The 5Bs can work in that scenario if there's 3-4 inches behind them, but it still won't be optimal so I think you'd still be better off with the 6LCRs. If the racks are open then that presents less of a sacrifice though.
As Nick said while it is ideal to have all of your speakers be from the same brand it is most critical to have your fronts and center matched.
Heh, Jason Hicks is pretty much the same as John Smith, there are literally hundreds if not thousands of us. One day when I have the spare time and energy I plan on hunting down each and every last one and forcing them to change their names. Because like the great film Highlander says, "There can be only one! " 
Jason Hicks
Aperion Audio Guru