It doesn't make much sense, to me, not to use digital servos for throttle/brake functions. I'd be really interested to hear why. Digital servos produce more speed, holding strength, and torque all across their range of travel, while analog servos do not.

Regardless, there is nothing wrong with some overkill. Many times it's a no brainer to just go ahead and stick the strongest servo you can into a model. Usuaully, the most torquey servos also offer the best speed, and at a minimal price increase over the next model down.

I just picked up a couple Futaba S9157 servos for my Losi 8ight. To me, it made more sense then the next best servo below the 9157. For an additional $10, I got almost 100 ounces of torque more, and more speed. Servos, like all electronics are an investment. If you sell a model, chances are you'll hang onto the electronics and use it in another.