My thoughts are pretty much the same a Grey Beards. I avoid extensions if at all possible as I have seen to many fail, especially those that are buried inside a wing or fuselage as, if not cycled often, build up a high impedance and cause servo jitter if not outright failure.
As to radio systems, I have one Futaba FHSS, one Airtronics RDS8000, one one Spectum. All are good so far but as an electrical engineer with many years in the RF field, I am partial to the Futaba or Airtronics as their frequency hopping systems are theoretically more reliable and more immune to possible interference than Spectrum or JR. I have not had the Airtronics long enough to comment on their reliability from an assembly and component standpoint. Futaba's long term use in the military work is particularly pertinent as to the reliability of their frequency hopping techniques.