with a 1257 and 58 tg in my nt1, no problem with a full days racing on one rx pack. 1300mah reedy life. dont have to charge it for an hours running.
you dont need a bec, just a cap. its very simple and doesnt cost $20.. the spectrum one is $6, or if you have an electronic supplier in your won, less for raw caps, just solder on tails.
all there is to it.