Thanks to Mike Lundy for sending me a couple of Flat 5 boxes to use for testing.
I set one up last night and used it for testing. It worked out great. This is going to make an excellent center channel. From the bottom of its range to 4kHz it was within about +/-1db. It handles the vocal region really well and was a dead match for the Skinny 6's.
I also built a make shift wall above and below it and tested it as an in-wall design. This drops the step loss compensation filter, and raises the sensitivity about 2db. It also still maintained the flat response. So for you guys that are looking for something to build into a wall, this might be what you are looking for.
These will have decent power handling, but not high power handling. They are not for high SPL applications. They are for clarity and a very natural and accurate sound. Also really good for small rooms, bed rooms, or rooms with little to no acoustic room treatment as the little 3" driver has a more controlled off axis response, and is not at all bright or hot in the top end.
Also, vertical and horizontal off axis responses look great. They will give a consistent sound regardless of seating position.
The complete kit includes all drivers, crossover parts, tube connectors, wire, solder, screws, heat shrink, and ports. Only $279