I flashed mine to 2.18 the day I got it. Still works perfectly and not one coaster yet

You should probably just hit up the NEC website. they give you all kinds of instructions. Probably just precautions, but I did it anyway just to be safe. But they warn you and scare you and freak you out with all the things that can go wrong when flashing your drive that it almost makes you want to just say forget it. But I risked it. I'm a risk taker.

edit: I'm assuming I used the windows version, but mine was downloaded from the NEC site, so I'm not sure which is which on that site. but I'd go with the Windows one.