Hi Doug,
Yes, there is not that much 'knowledge' out there re bipes.
I have been flying them for a number of years now and have gained some experience.

Any yaw stability , while using the contra, is most manifest while doing inside 1/4 loops to and from vertical.
I am trying a number of things, including more sweep, on this to try to get that better.

Any thoughts on thickness % for that section you mentioned for the stab ?

Btw I see on the Biside thread that it is recommended to set the top wing incidence at 0.5 negative relative to the bottom wing. I have been setting them the same as each other.
About 4 years ago I had them set like that ,but with less difference. To improve the yaw stability I moved to a more forward CG and it flew too heavy.

Thanks.
Brian