Well initially I assumed he was running 1/8 electric, and would run the receiver from the ESC internal BEC and the servo from an external BEC (see my first post) using his 4-6S main lipos. He agreed that was what needed to be done, as did others. But when it became clear his setup was nitro that solution became more complicated, requiring adding 2 regulators instead of 1 and didn't make much sense anymore.

I never suggested giving anything more than 6V to the RX.

If he were to give 8.4V regulated voltage to the servo it would need to definitely be a 3S lipo RX pack, in which case you'd need 2 regulators anyway. I run my HV servos to 7.4V because that's what the specs usually say (speed and torque ratings at 6V, and 7.4V) I think 7.4V is a good medium between 6V and 8.4V as far as performance and longevity. Plus the monster torque servos now are really starting to push current draw as it is, 8.4 would be more likely to overload BEC (not an issue with unregulated lipo RX pack I geuss) Anyway, I said that the varying voltage of using direct 2S lipo to the servo probably didn't matter much. I just never tried a 2S lipo RX pack because I run 1/8 electric and already have a 4S voltage source, for me it makes more sense to use a regulator.