Just my 2 cents
I have an 8ight-t with the 1515 1y, 16 tooth pinion, 5000 mah Neu 4S lipo with the Quark 125b. It is crazy fast, silky smooth, and I can get about 20-25 minutes bashing. I know racing uses more juice than bashing but if you are thinking 8000mah batteries you should be fine for 30 minutes.
With mike's or anyone elses motor mount you cannot use mechanical brakes since the motor is mounted where the throttle/ brake servo used to be. Here is an in-process picture:
