does this make sense?

http://45surf.smugmug.com/Other/dslr-with-hd-video-dslr-stills/45surf-double-45-dueler-TM/swimsuit/728931993_bkGWP-XL.jpg

http://45surf.smugmug.com/Other/dslr-with-hd-video-dslr-stills/45surf-double-45-dueler-TM/swimsuit/728931993_bkGWP-M.jpg (http://45surf.smugmug.com/Other/dslr-with-hd-video-dslr-stills/45surf-double-45-dueler-TM/10500745_mhoMe/1/#728931993_bkGWP-A-LB)

advantages i can see are that you can shoot continuous video while shootig continuous stills. and also get the af off the small camcorder.

disadvantages?

It doesn't really make sense to me. I don't really see how there are advantages to shooting like that, and both cameras can't be framed correctly since they are on different planes, and the weight distribution must make it difficult to get a steady shot on either camera.