I have been flying my kit TF giant 47 since 2003 with 70 oz servos on the elevators, 615 (old) on the ailerons, and std airtronics servos (42 oz/) on flaps, rudder and motor . Engine is a g-62 running a 21X10 prop with speeds clocked at 108mph. Well over 100 flights. I did have one aileron servo go bad, replaced it with a 42 oz std servo at the event and flew with no problems. My conclusion is that the recommended servo strength for warbirds is a throw back to the original IMMA recommendations in the late 80's early 90's when no one knew what they were doing and everything was overkill. I always thought that if I could fly a pattern plane like a Banshee with an elevator as big as one half of the 47's on std servos at speeds approaching 100 mph with no problems then why should I not be able to use std servos in a plane like the 47? A well engineered plane with tight surfaces should not require brute force servos. Some think because a plane is heavy it takes more force to move the surfaces in the air, not true. That same plane flew for many years on 72mhz with a 4.8v 700 mah nicad pack. Now on 2.4 I use a 2000 mah 6v nihm pack.