1st choice: Same speakers all around is the ideal. Usually doesn't happen because of space or budget limitations, or, if someone is a big stereo music listener and wants full range (and/or larger) LR mains up front.
2nd choice: Identical speakers up front LCR, identical speakers for surround/back.
3rd choice: Identical LR mains, horizontal center, identical speakers for surround/back.
Ascend, like almost all the ID (Internet Direct) companies, does not have resellers. Most have generous return policies so customers can audition their speakers in home.
Congrats on the Klipsch sub deal!