So the whole point of the Mantra is to be able to zip around an enemy base jumping on people as they spawn before they can even grab a weapon? Yea ok, not my idea of fun.
Never had this frustration from my many hours on UT2004, apart from at end game when a base is vulnerable, and you go charging in with the old Mantra to blow up the generator. Yes you can run respawning players over if they are not quick. But it hardly makes up a significant percentage of my kills.
I'm no fps God by any stretch of the imagination but the only time I get run over is from behind, during a fire fight on some node (oh, as a newb I was fender fodder for a while!). I can dodge almost anyone trying to mow me down in a vehicle 90 % of the time even with short warning, and, annoyingly, so can everyone else when I'm driving one. A base is more cramped for double jumping out the way but it's more cramped for them too.
Still, that's your experience, this is mine.
He may look like an idiot and talk like an idiot but don't let that fool you. He really is an idiot.