Ceiling Mounted Speakers for 5.1 or 7.1 Surround Systems

What experience do fellow Dopers have with ceiling (or wall mounted) speakers for use as surrounds in 5.1 or 7.1 sound systems? I am also looking for anyone who has installed or used Sonance in-wall or in-ceiling speakers (like the Original Series)? I am quite familiar with the speaker components required for 5.1 and 7.1 systems so please refrain from digressing on that subject!

Note: Not sure if this is the right forum but one of the mods will move it if necessary.

They work great. I have sonance in my house.

Do you have any specific questions about them or are you looking for opinions about them?

Both - your opinion would be appreciated and also, if you have Sonance Original Series Medium 624 do they have enclosed or open backs?

I installed these.

Not cheap. But I have no regrets.