After going through a fair number of Bipes, somewhere are 15 over the past 20 years, you're right about setting the upper wing with a bit of negative. I've found that everything from Aeromasters, bipe-stiks, even hog bipes really become a joy to fly once you get the incidences set properly, ie. a slight bit of negative. don't be afraid to shim the wing and try a bit more or less, it can make a big difference. Try some down and right thrust in the engine too!