I gave the pump idea a miss right from the start........and got a new Alu 12L tank. Its great, except for lugging to the indoor range for sighting and then to club day, and then,.......etc etc.
The idea of a Pony bottle does appeal for a quick light option doesn't it.
They are just as expensive as a big dive bottle here as well,.....might have to wait a while yet.
cheers
GS