David, no question there are good arguments for using a 5x4 back on a 10x8 camera; long lens use jumps immediately to mind. But, as with most things photography related there are tradeoffs. For example, I can put my Schneider 480mm Artar on my Arca-Swiss and it's solid as a rock. Put that same lens on my Deardorff--I wouldn't even pretend to use it on the Intrepid--and things can get shaky, depending on wind factors. The small 450mm Fuji C would be a better choice, IMO, in this focal length. I bet the Intrepid could handle that lens, too. Now that you've got me thinking, how about a 10x4 back for the 10x8? Now that's something I'd be interested in!