I have not built a kit plane, but I know several people who have. The only problem really with a kit plane is the testing phase. A lot of kit builders make the mistake and test it themselves. Obviously a mistake on that front, as either they have 100 hours or 1000 hours, but have only repeated the first 100 hours 10 times over. A tremendous lapse of judgment and an overriding vision of grandeur to test out a high-performance home-built civilian aircraft without a lot of experience with testing. I have a few buddies with thousands of hours TT and they will not touch a home-built plane out of fear. Everything has to be second nature and even then, spring-loaded to corrective controls may not work in a plane that has defects.