looks like you've been in this hobby 25 years but if you read the post located here it probably explains things better than I can.looks like some rx can operate at alot lower voltage than the servos.anyway I was going from memmory when kraft made the announcement that their seies 72 system would operate even with a bad cell in the flite pack where as my series 70 would not.I did have a cell go bad in it and the result was that while the servos would move they would not return to neautral on their own.returned to kraft and a bad rx pack was replaced end of problem.so I would have to say that rx was still working on 3 cells and unless technology has gone backward since 1972 I would think rx made today should still work on 3 cells.again servos require more than the rx so even if the rx works on 3 cells servos could or could not .I would wonder if the digital servos are capable of reduced voltage as they seem to require more mah capacity rx packs.
http://www.flyinggiants.com/forums/f...r-voltage.html
http://www.flyinggiants.com/forums/f...r-voltage.html
replace the **** with flying giants no space