.15 is just at the point of being difficult to drive. I would never pay for a servo with .15 speed and wouldn't settle for it.

the 125oz torque of your servo is actually pretty good. The traxxas are a bit heavier and probably require the torque but I'd say if your 125 or more you're doing good.

That .08 speed will be VERY noticeable.

Give it a shot and post back.