depends what you are going to do with it.. the stock cranks have been proven up to and over 750hp with the right preperation. i cant remember what they cost off the top of my head (something like $1800 i think?) you could prep a few standard cranks for that price.. in saying that i was going to use one, simply because i was buying a bare block to build up, i also had a fairly hefty turbo that i wanted to spool as quick as possible, was also going to run nitrous.

So in 95% of applications you dont really NEED a billet crank, but if money is no objective, then why not?