I've found FUD to be somewhere between resin and plastic in its durability/detail. But it's also very much its own unique material. Obviously you don't get print lines in resin (they're very slight in FUD) but FUD doesn't warp or have flash or mold lines.
FUD breaks off the sprue by hand and leaves pretty much no discernible mark. Plastic requires a little more loving.
Resin has a mold release compound that must be washed off, and FUD has that waxy stuff that's similar.
You can get geometries with FUD that simply aren't possible in plastic or resin. But those shapes tend to be the ones with the pointy bits that break off in transit. I suspect that plastic subject to the same constraints would also break. I've had stuff break in transit or even in production, but once it's in my hands I find my plastics breaking more often. My experience is that overall durability is similar to plastic.
Resin and plastic are much, much cheaper.
I have a lot of Einar Gosric's 1/270 space fighters (
link). Several have moving and/or interchangeable parts. The parts fit perfectly without filing and there's no rattle. You simply never see that even in plastic. Even with precision models you need some loving to get stuff to fit perfectly. OTOH, some sharp surface details can be slightly fuzzy depending on the printer orientation (designers have been lobbying shapeways to be able to determine print orientation themselves).
Bottom line is that FUD is ideal for most gaming applications, EXCEPT for the price. To me, it's what you use for very special purpose minis that aren't going to be made in bulk. Without shapeways, these either wouldn't have been made, or would have been produced at a loss.
