I'm new to HT and wondering if you could help me with a question I'm pondering...

Is it wise not to have your rear surrounds match your front right/center/left?

What do you really lose?

The pitfall you avoid by matching speakers is a seamless soundfield when something moves from the center speakers to your rear speakers. If the speakers are very different you may notice a change in the quality as an effect moves between speakers and can take you out of the experience if you are bothered by that kind of thing.

In an ideal scenario, all five (or seven) speakers would be identical so that they are all "voiced" exactly the same - producing the seamless soundfield that lanion mentions. As a sound effect or other bit of audio data moves from one speaker to another, the playback would sound the same and thus be more immersive and convincing. In reality, getting identical speakers all the way around is a very difficult task, especially in systems that have to share a space with other day-to-day living functions (such as when the theater is in a living room). That's one reason that speaker manufacturers routinely design families of speakers that share similar design traits (same drivers being the most obvious example) - even if you can't use the same model of speaker in each position, you can at least use speakers that will blend as well as possible and thus preserve that soundfield as seamlessly as possible.

Thanks for the responses...

I believe I've seen some people with different makers of fronts and rears...So it sounds like people do take the plunge.

How much are you compromising? And is there a way you can try and match different makers as close as possible?

Having actually made this compromise, I recommend a bit of caution. In my case, my side walls presented challenges that prevented mounting my Studio ADP surrounds and I wasn't in a position to purchase Studio 20's (even assuming they would have worked, which I doubt), so I was forced to use different side surround speakers in my otherwise all-Paradigm Reference system. I elected to use Axiom M3ti's because the driver complement was relatively similar (1" metal dome tweeter, 6.5" woofer) and the two companies share a similar design methodology (both being Canadian companies that have made use of the NRC research and facilities, although Paradigm now has their own test facilities). Even still, I noticed a difference when changing from dipole Paradigm surrounds to direct-radiating Axiom surrounds. It's fortunately a subtle compromise in my case (and likely due as much to the change from dipole to direct radiating as to the speaker manufacturer), but one that I at least was able to identify.