I've used this one setup for a while. I switched to the set up the Dive Gear Express. The DIY one I didn't feel comfortable carry my bottle using the handle (which it is not intended to be) where as the DR one is solid and you can easily use it to carry around your bottle.
I've not seen the Halcyon one though nor the one through Diveseeker.
Has anyone used the DIR Strap that Dive Gear Express sells?