ob1,
You have brought up some excellent observations and comparisons here. Leaving "brand bashing" out of the picture, I cannot imagine why any digital servo with a 140oz plus rating would yield to light pressure. You may have found the root of Neos' problem.
It would be of interest to anyone using this particular servo to see if this weakness would be consideded "normal" by the manufacturer. It would be better if someone who is using them were to contact Hitec. I know if I was experiencing this with an 8611 I would be on the phone to Horizon first thing in the morning!
I enjoyed you description of uses for the 425s' and 811s'. It was not only descriptive, but accurate.
Thanks for you post and observations!