They don't vibrate. I have one and it has never viberated. There were a few who had a problem with there drive shaft. And the reason for that was because they had a balancing machine that was out of spec and caused the balanced drive shafts using that machine to be not so balanced. This was fix right everyone who had a bad drive shaft got another X-File TT.NET Case closed..
And personally I love the driveshaft. And at about $350 its a good deal..