To be fair, I too prefer the 57 to the i5 by a hair. But most of the more "metal" guys do seem to prefer it - it's a little brighter which allows you to position it a little closer to the edge of the cone for a thicker, smoother sound, and a little more scooped in the mids which if you're after the mid-scooped metal thing is probably a plus. The 57, meanwhile, does have a little more midrange to it, but also just seems to sound "crunchier" overall. I don't like it much for leads, but it's just a very natural sound for a guitar.
and really, either ought to work for growing, but the slightly brighter high end of the i5 might give it an edge there too.