I dont know about the later stuff, but the 250 was built out of some quirky kinda plastic called 'Staren' which was supposted to be scratch resistant.
That said, the old beastie aint got a scratch on it despite the occassional catching of the surface by the carry case zip when extracting the unit from the case. So i guess 'Staren' is scratch resistant.
Hmm, but would it stand up to a grinding wheel.. or sandpaper..??
FG