I certainly have! Actually it was your GTP that got me back into the hobby after a long hiatus. I bought the kit, built it, painted it (looked great), and crashed it on the first flight. I suspect from a combination of high build weight, aft CG, and pilot error. I ended up building 2 or 3 more GTPs out of foamboard and really had it down by the last one. I've been iterating on the design ever since. The biggest changes being redesigning the steering geometry to mitigate wheel translation and in the airfoil, which was adapted from Lee Woodworth's 'Gull':
The one thing I've never been able to make work, but am determined to make work, is a thrust vectoring EDF-powered flying car. Ever since I installed TV on my Avanti it's been practically the only thing I fly, though I'm convinced that it would be better served in car form.