Kevin,

Like Jeff, I have run the 3421 in most of my pylon apps from Q40 to warbird stuff for a while with no issues ever.
I am running the new JR DMSS equipment. If I need tail weight I too will run the std 821 servo.

I have discovered my favorite set up for pylon is now the following:

RX: is the RG613BX 6 channel that requires no sat rx- simple and clean set up, and can handle dual ail servo set up if you want flaps.
Of course JR DMSS has Xbus ability so you can run any amount of servos thru it and utilize one channel on the rx.
As with all the new JR DMSS Tx's and rx's they have built in telemetry capabilities, such as rpm, heat and pitot tube for mph.

My new go to Servos: are the 3711 HV
- you can run up to a 4.8 to 7.4 lipo with no regulators needed, but I am a fan of the 6.6 life batteries and these servos are 86 oz torque with this btty. They also only weigh 1 ounce and are very fast, metal geared servos.

My switch is always the JR heavy duty with charge jack.

My battery is a 6.6 2 cell life 700 size up to a 1200 size, depending on retracts (mech or electric)

Mt transmitter for most pylon is the XG14
I have a few on the 28X and even some as a back up or loaner planes on my XG8.