I went with the ax as I have one and it has seemed to be plenty
Patch is the best man to answer this with his 4x exploits I am sure he pounds them pretty hard.
If I was to buy one today I would probly roll with this 4x30A per rail monster
ENERMAX MAXREVO Series EMR1350EWT
http://www.newegg.com/Product/Produc...82E16817194092
http://www.techpowerup.com/reviews/Enermax/EMR1350EWT/
they may have a 1500 on tap