I would go with the JR 1221X, 12 channel. Probably more channels than you need right now but might as well have them for a few extra bucks. You can plug your A123's through on/off switches right into the rx (although some guys prefer to use regulators). You could also go with the more expensive 1222X which uses a "soft switch" if you think you will need higher current capacity for future jets. Both these rx's are compatible with DSM2 and DSMX technology, depending on which version your 12x transmitter has.