
a. It does not react to hairspray, or many propellants
b. tears, doesn't grenade
c. is lighter
but I have heared that pvc is better for combustions for many reasons, too.
like:
a. better pressure resistance
b. more widely available parts (this is more people's personal experience than anything)
c. the fittings are sometimes cheaper (once again, personal experience)
but, pvc is better for pneumatics.
do the math. there is really no science to it, just personal preference. stop being idiots.