Hi James,
Take care of the knee!
I'm looking at a full replacement on my right knee at some point in time. No cartilage for 40 years now, and lost the ligaments in it in '07, so it ain't real good anymore! But I have a custom made *Carson Palmer* "Breg" brace (cost the insurance company about $1500!) which has kept me going.
As to either of the Werwage planes you mentioned, both are excellent as designed. The "XL" we built used a Geo Bolt wing per Billy's suggestion, and it was very good. The basic wing in both planes as designed is the basically the USA-1 wing, so efforts to keep the weight around 60 oz, (or less) is a good idea. Billy's designs DO rely on light weight.
Jim is a great guy, so get hold of him if at all possible.
Bill