I'm running the GTB. It comes with the capacitor and the fan. Its a reputable company with reliable warranty support and tech support. Mines about a year old and I've had no trouble with it. And to top it off you can run 13.5 thru. 3.5.
As far as I know any of there motors will work on it, and brushless has a lot of perks more run time and less maintenance. And if the brushed motors are your thing the GTB has that covered as well. You can run brushed motors on it to.
All due respect Tekin is a good speedo to. I used to run them years ago. I also ran LRP. But the GTB has all the whistles and bells right out of the box. Money better spent On the GTB in my opinion. The fan is optional you can take it off very easy. Good luck a person can get a headache deciding on this stuff.