[BrianG]

I think it depends on your goals and usage.

If the goal is a simple setup that has as few parts as possible and/or ease of disassembly, then motor brakes is a no-brainer. No servo, servo mounting, linkages, discs/pads, and wires to worry about. And, fewer parts means fewer points of failure. However, the back-EMF spikes tends to be harder on the ESC and batteries.

If the goal is to achieve maximum tuning, then use mechanical brakes. Gives the ability to change front/rear brake bias. However, there is brake fade, not to mention more wear items.

As far as runtime, I think it's a wash either way, or any difference is neglible. This was discussed TO DEATH in another thread and I don't think it ever went anywhere.

If anything, try it both ways and see which one you prefer. I personally voted for motor braking - not because it is "better", but it fits what I use my vehicles for.