Gilbear

Yeah Ed, the backing out through the cut has seemed odd to me. I've always been told not to do that, and on other joints or routes it's usualy made things too loose for me - but for some reason it's what they do and what I've done as well with their set-up (one is almost forced to do that on end cuts with their set-up when using dovetail bits) and it works just fine! I suppose it's simply a matter of the mechanics of trying to lift out at the end of the cut without damaging or hitting the right angle fixture.
I often use a sliding home-made jig for straight finger box joints on the router and if I back out or repeat a cut, my joints are too loose - maybe it's do-able with theirs because there's so little play or shift to their jig, and the work piece is clamped in as well so it's not going anywhere. It's a relatively new purchase for me so I'm still getting used to it, but so far so good.

Bobj, I agree it's a little pricey (hmmm, not as expensive as some of the dovetail jigs I've seen, particularly when you start adding diferent templates), and you could make something similar fairly easily. What might be difficult is to acurately make your own registering teeth. The Incra uses teeth milled on 4 bars that are aligned on the upper and lower halfs to lock adjustments in 1/32" increments - you can return to the same location essentially balls on - there's no trying to eyeball a ruled line where paralax comes into play. Not sure how I'd accurately make those locking teeth, but maybe some more experienced guys here would have some ideas?