As the five-star review shows
here, the Mezzos are definitely not an unknown. Another five-star review(for the £800 floorstanding Mezzo 6) in the current issue.
We haven't tested the full surround package, however- that's coming up in our next issue, as part of a full-size speaker package Group Test, out Sept 18th.
I'd also wait on the reviews of some of the higher-end new amps from Onkyo, Yamaha, Pioneer etc before buying a 2007-vintage Denon. Things have come on a lot in a year for AV receivers!
And as Hi-fi Nut says, auditioning is a must...