Great report Mike..!
No doubt this is a great "Motor Sport" once you get interested in the engine and prop work as much as the actual flying.
With the added ability to clock speeds right there at the field and film the results, it has really expanded the hobby for a lot of us.
I'm still mired in a nasty automotive project [building a console and speaker boxes out of plywood and FG] and am looking forward to getting back to some Speed Delta flying.

Oooops.forgot to ask about the single fin. Did you see any signs of "swimming" or fish tailing at any speed...?
What are the dimensions of the fin...?