RE: P13 Reverse Spins
Hi, I have experienced exactly the same with my Valiant, which was also set up as per Bryan's incidence and CG recommendations. I tried all sorts of things to get rid of it, but it was noticable especially in light wind conditions. I know of some pilots that will do the second spin as a negative spin, whereby there is no jump forward as the spin direction changes. Only a really sharp judge will pick it up, but if they are looking for that cheat then it's a sure zero. Certainly less elevator helps reduce the tendency to jump forward during the direction change, but you still need enough elevator to enter the spin, especially in calm conditions.
I've only just started to fly a Peridot, and I was pleasently surprised to find that it has less of a tendency to jump forward during the reversal. I don't think it has quite as much +ve incidence on the main wing and CG is a little further back than the Valiant (my Peridot has a small tuck to the wheels on L rudder KE).
Regards
Clint