I think it is important to note that there are a number of very different Kitfox models with very different qualities. I have no firsthand experience in any of them but have read quite a bit about them. I believe he Models 1, 2 and 3 did not handle all that well. The 4 or classic4 appparently was a major improvment and the current (bigger) Model 7 is better still. There is some good info on the Kitfoy website and there are builder/owner groups with online forums etc. Just google a bit.
There are also a range of engine options to choose from from 2stroke to Lycoming and everything in between.
Are you looking to buil one from a kit or buy one that has been completed by someone else?