The Rotec really makes the Kitfox a neat-looking plane. I guess I'll reiterate what others have said: Do what makes the most sense for you. But I will also add that there are considerations beyond what you want in the finished product. Kitfox sells Firewall Forward for the r2800, but you'd be largely on your own for the r3600. For me, this is my first build, and I bet a lot of money against poor odds that I'll finish. So a major consideration for me is to stick to things that are tried-and-true and well-supported by Kitfox. The round-engined Kitfoxes are beautiful though, so I'm glad people are out there doing it.