With Fontext I initially sold it and managed to sell over a 100 licenses, which encouraged me to support it etc. Then I made it freeware as I'd covered my costs and a bit more. I think doing it this way round might be better than donateware.
arent you fooling your customers that way? and: will it work more than once? i mean: if i know, you're releasing your prdocuts for free after some time, why should a buy it now?