I am under 35...for that age group I think it was high 50s according to sart. Since I was 29 at cycle time, doc said 66% chance of success. I was successful on first try but not sure of accuracy of 66%. As for gender selection, I would assume it is a little lower since you knock out half the embryos:) Hope that helps!
As an fyi, I went to RMANY because they have the highest chance of success in NYC for my age group. A lot of people also go to NYU and Cornell and they have very high rates of success too. I heard both of those places also do gender selection now and are wonderful places, so I'd check into there also, as I am not sure the price difference among the three! Good luck!