Hi Christopher
I have watched all of Rob's videos on building shooting boards. The bowed design refers to adding a hollow to the main platform's substrate (not the track), as I recall. I have built many shooting boards over the years, as have others, and none have a built-in bow. Strangely, they all work accurately. Ergo, the bow is unnnecessary, and I conclude a gimmick to say "ours is built better".
Regards from Perth
Derek