I am also using a 171 sv on rudder on a monoplane with no problems in the F sequence. My brother has the same exact plane and setup except with the 175 sv on rudder and we cant feel a difference between the two in flight. Plus the 171 is only 48 grams or so.
Caglia
I think your into some there , we dont need the servo power that they need (do they) on the imac machines ..we dont need 250kg servo power on throtel..ehh just a joke...but what we need is precise fast and sloop free servoes, its not a bad thing if they not weigh over 50 gr each