Pirate, you're correct - I failed to describe a mount. I do not anticipate using a waist-mount, per George Irvine's photos on the WKPP website. Instead I'm considering the arrangement shown by Uncle Pug in his photos on an earlier thread. In his case the bottle is attached to the backplate using a web loop and bungee cord set-up.
The external diameter of the 6 cuft tank is 3.21; while the OMS runs 3.58. The delta is .37", not real significant, and the overall length is approximately 11.2" in both cases. Bouyancy empty is -1.14 for the former and -1.61 for the latter, also reasonably close. Hence its really 4cuft versus about 6.+ cuft that seems to be significant.
Mike, I also currently have the Luxfer 2015 psi aluminum 14 cuft tank mounted on my doubles. I'll be diving two different sets of doubles, twin PST steel 95s and twin Luxfer aluminum 63s. The 14 cuft tank is a bit much for the 63s, and won't fit well on the backplate. So.....
I share your concern with a 6 cuft 3000psi tank that will seldom hold more than 4 cuft at argon pressures. The OMS tank, like the 2015 psi Luxfer, will generally provide better fills. Might last a weekend if, like UP, you purge from another source.
I just hadn't heard much from anyone who used this bottle. Particularly anyone who had tried it and been dissatisfied for some reason.
Mech - thanks. If I go this route you'll know how it goes.
I appreciate the responses from all. :doctor:
Doc