To be honest mate, it's the best "budget" amp I've ever heard. I had a discission via e mails with Andy Fov the other night (he's also a 811 owner) and he too couldn't praise it highly enough. For £305 I got 7 channels at 100watts into 8 ohmms, though the THD is 1%, which is consodered quite high. For example, the THD of it's bigger brother, the 2011, is only 0.09%!! However, that IS an outstanding amp. You also get Dolby Digital EX (official licence), Pro Logic II, DTS, DTS ES Discrete, DTS Neo 6 and a reciever.
I owned the Marantz 5200 and 7200 previously. They to are packed recievers and they do a lot, but, to be honest, they don't do it to well. The 811 does everything well.
And, as far as I am aware, you can't engage the midnight mode in stereo - only in Dolby Digital. It's actually a spec of DD.
One reviewer commented on the poor processing quality compared to his old Sony 555 eh? Why did he change the 555 then?
Surround steering is spot on with the Pioneer. On the set up side, my main criticism is speaker distance - this is measured in .3 of a metre and not .1. A small niggle but 20cm in sound delay is quite a delay I would imagine.
And it does have the A/B speaker switch for other room listening.
Whatever you do, don't try and compare the 811 with your Denon THX amp - there's probably about £1500 difference in price. No comparison IMO.
I use mine with a complete Mission 77 package - with 774's on the front and a single Boston VRS micro for the surround back. It does give you the option to use 2 though.
Try and get a demo and let your ears decide.....