....just wondering WHY the interest in such a tank ? You're never gonna get a fill to anywhere near that pressure anyway...not to mention the fragile nature of the tanks and their added expense ???
I believe that some of the fire/rescue air packs operate in that realm and is probably the origin of the cylinder technology. If the dives shops are providers to those services then they can service divers in that same range. If the local shops are not servicing those other markets then I agree that getting 4350 fills will be very difficult. Locally 2/3 of the shops are not prepared to fill such a cylinder.
As for LP cylinders, most shops will not provide a 3000 PSI fill so take that option with a grain of salt. Again in this case one shop may indulge and the next one may not even acknowledge a + stamp.
This Luxfur product is a nifty cylinder but has way too many limitations and costs to make any sense to me. If a steel HP 80 or 100 is not an efficient enough package it's time to look at why.
Pete