1st, the new hp steels are less than 3500 psi (I think 3350), so the pressure should be no problem on the equipment when you figure that most of us pump our Alum 80’s to that. The benefit to the lp steels is that any boat compressor can giver you a perfect fill. Also over filling the lp’s gives you substantially more gas, where as with the hp’s you really cant overfill them (remember, you should never over fill tanks, very very bad!).
2nd, my question would be, why do you need all that gas? My double 80’s have provided me will plenty of gas on all the dives I have done down to 260’. But double 120’s will be more than enough for anything to 300’ +!! My preference, if choosing steels, would be for the LP’s for the above reasons. Just make sure that you can swim the rig in the event of a buoyancy failure, and more important, how much air you need in the wing to keep you neutral throughout the dive, the more air the greater drag. By the end of my dive my wing is nearly empty. Good luck.
