I have some and am replacing them as I renovate. The problem with them is that if you stand under one speaker, you really get too much localized sound from that channel only. The only way to effectively do in-ceiling is either with dual voice coil single speakers or go mono. I just replaced really good niles speakers with a single Martin Logan dual voice coil to eliminate this problem.
The other room with ceiling speakers already is renovated. I intend to get another martin logan and use the other hole for a subwoofer(it's the top floor of my house and the attic should make for one heck of a baffle).
The other room with ceiling speakers already is renovated. I intend to get another martin logan and use the other hole for a subwoofer(it's the top floor of my house and the attic should make for one heck of a baffle).