the banjo bolts often block up and dont flow that much air at the best of times.
the push fittings are much larger bore so if the axle gets a good suck on the will help to stop it vacuuming.
i thought the fittings wer 1/4 bsp tbh, but im not sure (just what i remembered from the ebay listing)
i bought an ebay kit for piece of mind, but now i would buy 4 elbow fittings, a 8mm-6mm reducer for the fuel tank, and 30mtrs of 6mm tube for about 15 quid, the whole lot will cost about 20 quid...
cheers, sam