hmm, le gits site won't load for me..
It sounds tough to presureise it from empty, how about just topping it after taking 300 shots?
The thing that doesn't put me off is that the bottle gives so many shots per charge, its something like 300+ full shots? I rarely use more than 100 on a shoot anyway, so one charge could last quite some time.
Do you still use a pump nigel, or have you bought a bottle?