Start at the defaults
I fly GRT HXr with GRT pitch and roll servos in my RV-8, and while I don't recall exactly the settings, none are more than 5%-10% off the default. I would recommend starting at the default (100%) and fly it. They are easy to adjust airborne. Of course the 9A has different handling characteristics than an RV-8, and certainly others more experienced may have a different opinion. In any case, this is quite easy to arrive at your optimal settings through flight test. Remember to check ALL modes as you may likely need different performance in different modes.