Originally Posted by DjAlusiv

Contrary to that, I have been running a Castle MMP w/external BEC paired with a Tekin PRO4 HD 4300. It has explosive torque and speed that is beyond the scope of racing without tuning it down (with a 21t pinion I had way too much top end and more than enough torque. I replaced it with a 15t pinion and still have more than enough speed for the longest straight and I have been slowly molding my torque curve to a controllable level.) We actually were just discussing this as it is a new application for me in the Tekno. I have been using this ESC with various combo's since I reentered the hobby and have had a lot of luck with them. I have three MMPs and they are all working flawlessly and efficiently.

edit: You are going to find opinions on this matter all day. Just have to choose what option is right for you. I would start with the most cost effective option and bump it up if necessary. Not sure if you have more than one kit, but I usually try to purchase my electronics so that if it does not work in my primary racer, I just upgrade my non-race kits.