I was driving my 66 Vette, years ago, and got hit by lightening. Don't know if it was good that it was glass, or bad. But all the wiring was fried, and I wasn't!
Back to keyboards, I'd rather have lightweight plastic than heavy metal (even in music), but then I don't keep 'em very long either way, and I take really good care of my gear. I've found that if a fight breaks out you can get more speed running with the plastic ones under your arm.
Wasn't it metal parts that blew off the space shuttle? Maybe if they'd used plastic . . . Naw, that's not even relevant!

DonM