Got it. I get the point about digital working or not with nothing in between. I learned that when I went to digital flat screen TV's at the house.
My main concern with the 2.4ghz receivers is that (as has been pointed out) they will drop out momentarily during a servo stall, or even during a hard manuever if the RX battery is anywhere near being on the low side.
It's not that I ever try to squeeze every last drop of voltage out of a charge, but that those momentary voltage drops that I never noticed with my 72mhz systems will become a major factor for losing aircraft when flown on 2.4ghz.

I've been using 6v RX batteries for years already, so I think my strategy will be to continue to do so.

As a side note, I have to wonder why a 2.4ghz "needs" a particular voltage to work anyway. What I mean is that if a 2.4ghz receiver were to be designed to work within a voltage range of, say, 3-6 volts, then that would guarantee that the servos would fail first, but gradually, and that would allow the plane to be landed while still under radio control of the RX that would still see 3+ volts and therefore not drop out.
Just thinkin' out loud...

Edit:
In the mean time, I ran across this: http://www.airlandseahobbiesinfo.com...erd-airplanes/
Based on that information, I think that my strategy will be to continue to use analog servos (all my servos are analog to this day... no digital) so that I can safely use 6V RX packs to ensure the integrity of the digital RX while at the same time not having to worry about burning up any digital servos.
This still brings me back to wondering why RX's can't be designed to operate with less voltage than they do now.