Hi Dan,
Back in the day (early '80s), the torque rating on my Futaba S131 servos was 42oz/inches at 4.8 volts (the only option) and those worked fine in 60 powered pattern ships. Increased torque and speed along with ball bearing supported output shafts provides better resolution. I fly mostly high end digital servos, but still some good quality analog servos in my sport airplanes. I flew an old MK Wild-7 which had old (like 25 years old) but top quality at the time servos (Futaba). The airplane flew fine, but I felt like I was flying in mud because the response was noticeably slower that my other airplanes. Lastly, I have never run 'cheap' servos; so I can't really address their performance or durability. I have servos that continue to perform well after 1,000 flights in a glow powered pattern ship. The engine is soft mounted which is certainly a contributing factor.
My 2 cents worth... :-)
-Will