Air bag ?

[project 67 sub]

when i get around to bagging my burb, i plan on running nitrogen most of the time, and a compressor for those special occasions where i might run out of nitro. im am looking to go with a 600 psi bag so that i can turn my pressure up to about 450-550 psi when i might want to play with the switches. so here is the question: what is the better 600 psi bag to use for my burb, the $160 slam specialties Xs7's or the $80 Airlift Dominators? oh and another question: will dot line hold that kind of pressure(600 psi) or will i have to go to hydraulic line witch i would prefer to use anyways?

p.s. thanks in advance