I have one each of the Slimline Electric Pumps that screw on the Plastic jug and one metal sealing cap that fit the plastic jug. I have used their electric for two years without any problems. I personnally like the cap and manual pump arrangement as there is no battery to lug around. Something you might want to consider: I purchased both types to fit the plastic jugs and then the fuel containers (Power Master) turned into metal gallon cans. I now have the wrong type and have to transfer the fuel to the old plastic jug. Slimline makes caps and pumps for the metal cans also. The wave of the future is metal due to EPA regs I am told. Their reliability is excellent. Here is the link for the two products, listed under Fuel Pumps.
http://www.slimlineproducts.com/rc_plane_intro.htm