I've been using HT for years and love them, never a fail or centering problem. I used the new titaniums on my 25% WH Yak, Yes that's a lot of overkill, BUT, when I move up I won't be buying another set of servos. It's an investment, and still cheaper.
If you go to http://www.hitecrcd.com/servos/list open the PDF with the entire line, I suggest first going down to "digital", next go down to min. torque/speed. FYI HT is the only one whos 6Volt specs I trust, many do not even provide them. And there can be NO reason for not running 6 V on anything over 60 size (maybe a pylon racer).
As said, the decision is yours, but this is my experience.