The test video was not mine so I dont have any other info, you will need to search for that little T tail glider to find the originator
I reposted the video to youtube as the original was slow to upload.. there were other vids with other step locations, you will see his info says test 3, where was test 2?
cog... on the tests not known... but your cog will obviously vary with step location, and personal preferences on how you like the plane to fly..But as with any design start with a safe forward location or whre the plan specifies and move back slowly untill its as you like
edit.. with only a vague memory I finaly tracked down the man who made the tests.. Mr Doug Montgomery
... check out his various KFm glider build threads including the depron dynamite dlg.
here is the tests thread.. http://www.rcgroups.com/forums/showthread.php?t=629435
I read up on Dougs many build some time ago when I got interested in the DLG idea, but at my age twirling round to chuck up a glider just knackered me out so I went back to getting them up with a motor... much more suitable