Don, the Madison Dealers definitely do fail the riffle test -- if they didn't, it would have taken my 9 year old cousin a lot longer than 7 or 8 seconds to spot the markings.
The only deck with a "readable" back design that I know of which truly passes the riffle test is the Sharps.
Going back to the Aquilla deck, even if it doesn't pass the riffle test, it's still really cool back design!