I love the system! I have a BK600 with a BK HD6, I use 5 keypads including one in the Home Theatre, I also use Universal Remote 850's as they go well with the keypads and use the same programming. , the IR distribution works great as you can hook targets straight up to the BK and integrates well with the Theatre . The sound quality of the BK600 is actually stunning. I love the system. I did all the work my self. Very flexible the presets allow you to play video from one source and audio from another, which we really enjoy.
In the end we use remotes more then keypads (I don't think that is a reflection of the BK keypads), later I will work with the rs232 programming and maybe add some touch screens and PC control but that is down the road a bit.
The PC setup software is very useful, I gotta run but let me know if you have other questions. I would get this system again with out a doubt.
By the way AVS is a great place to get your BK stuff.