The main issue I can see is finding one that comes with a stack of receipts that would allow me to keep the Mazda engine warranty.
I like the idea of them a lot, I'm just not sure that it's worth buying a low-mileage example (there are several for sale out here, mostly 2004s though) unless I can (a) get it checked over by a rotary specialist I haven't found out here yet and (b) it has complete service history to Mazda's liking.
