Chess is correct and I have demoed Silver FXi surrounds. It is as powerful and has wide dispersion with great clarity and detail. The only issue is the price at more than twice the QS8. I personnaly could not tell the difference when both where only 1 - 1.5 feet above ear level. But if you plan to place the speakers 4-6 above listening level I would tend to reckon the qs8 would do a better job since the drivers are firing down and up rather than the bi-pole di-pole speakers the MA has.
http://monitoraudiousa.com/products/silver/index.html
The only rear surround speaker that I have demoed which seemed relatively close in price to the qs8 with slightly less ummppphhhh is the Warfedale Diamond surrounds. Qs8 detail is a little higher.

Saturn

Thanks for the Monitor Audio link. Yeah, the Silver FXi looks like a typical wall-handing dipole/bipole design. I believe that quite a few brands have surrounds similar to this, including the Boston Acoustics and Onyx Rocket just to name a few. The Axiom QS series is quire different, though...

When I move, I'll spring for a pair of QS8s. In the meantime, I use a pair of Mission 77ds, a good looking wall hanger with a pair of 100mm (4") drivers and a pair of tweeters in bipolar configuration. They actuall sound terrific. They originally listed for about $350. Could be found on ubid for a while for about $40 a pair.

Tough to beat close out prices of discontinued speakers being dumped on internet jobber sites.

Similarly, Michaura speakers which appear to have used the same drivers as Axiom uses (5.25" and 6.5"), in very rigid hex shaped cabinets covered in beautiful rosewood like finish, came in M22, M50 and M60 like configurations. These speakers were blown out by ubid for as little as $19 each for the M22 like M55s, $50 each for the M50 like M66s and $100 each for the M60 like M665s.