FireWarrior rapidfire wouldn't do much good at all against an army of necrons. Let's say you have 48 firewarriors. Thats 96 shots, 48 of them hit, 24 of them wound, 8 of them fail their armor saves, and 4 get back up. So out of 96 shots you kill 4 necrons. Not to mention, they can deep strike in, shoot up what they want, then you get to shoot them back. If you put the Tau all in vehicles, you can avoid for awhile, but what good is that doing? Without any good ap3 weapons, what hope is there? If you can convince me, have at it. I don't even play Necrons, I just know most of what they can do.