I can't really tell from that link what you're looking at but...
This is the best pony mount on the market
Welcome to TigerGear...the best Pony Bottle Rapid Mounting System on the planet!
(also the most expensive) but it'll last and never break. The most that will happen is that you might get a pin pulled out and lost by an over jealous diver - we've had 1 occurance of this in hundreds of evolutions. Get a couple of spare pins and you're set.
There are other mounts on the market which are nearly as good. I'd go with the metal ones as they are more stable although avoid the ones that are spot welded as they could potentially break. There are a number of fabric mounts that are very inexpensive and will work but the tank will flop around considerably
Also make sure that the mount will actually allow the pony to be removed by another diver in blackwater conditions - having a bailout is of no use if it can't be removed from the rig. The halcyon mount is designed for small suit gas cylinders for tech divers (6 or 9cuft) and is not meant to be a quick release u/w as we'd like for PSD
The reason why we don't like slung ponys like a tech diver would sling a stage is that most of the time we are trudging up the bottom which would place the stage right into the silt/muck/goo - not a happy place for a backup system. If you're only going to ever search mid-water in great vis (ie - carribean) then this might be an option.
The 13cuft is a good size for most PSD's and it will work to 60ft - anything deeper and you should start thinking of a 30cuft.
Don't worry about being able to remove the pony yourself - this is what the back-up diver will do. I haven't seen a system yet (back mount) where a diver could effectively and consistently do this without his trim being completely out of wack. If things get real bad, you're better off stripping the entire rig and pulling the pony then - should also be practiced in the pool.
hope that helps
