At one point I was considering building some DIY loudspeakers. I did a good bit of searching on the net. Ended up compiling some of the info I found on a little web page of my own. While I don't have any info on the specific kits you have in mind, you still might find some of the links useful.
See http://home.earthlink.net/~etunstal/diy.htm
[This message has been edited by Ellen (edited June 19, 2003).]