I just recently got my first truggy, a hyper ST pro, I started testing it with a cc/neu 1518 1y 1800kv with turnigy 6s 4000mah 40C battery. The motor has plenty of power and the truck would wheely/flip over backwards easily if enough throttle was used.
I also had a feigao 580L 8L which I have seen power heavy trucks, but still most people say its no good. Kershaw Designs seems to be the only one to believe in this motor

I wanted to make up my own opinion and switched motors in my hyper ST to the feigao.
Esc settings were the same for both motors, normal timing (10) and 50% punch control being the most important ones. Also I used a 16t pinion on both motors(I would have used 15t with the feigao as I expected it to heat up more, but the big diameter of the motor caused it to hit the rear brace if I used 15t. So 16t it was then.
The car launched just like with the 1518, the feigao could throw this truggy around like a rag doll as you say

I drove a short while before my rear internal diff gears were ground to a dust/oil mixture. I fixed this with a new diff, and on the next run, again the feigao motor was just great! I didn't feel any shortage of power, IMO both motors are slightly overkill for the truggy.
I drove for 20mins before LVC hit, and the temps were all good. The battery and esc were both under 100f(fan never came on) and the motor was a little high 160f. The 1518 after a similar run was about 140f. Two more runs showed about the same results, and I am now going to use the 580L as long as I can, and have the 1518 as my backup. The 20f difference in temps isn't much of a problem, and I expected this since the feigao is cheaper and also since its a 2 pole'r.
With the 1518 the esc and TX would need to be turned off and on agian several times during the run, but this problem didn't show up with the feigao. I would probably find out what caused it if I fiddled with it more, but I'll drive the 580L now anyways.
Hope this one positive report makes people try this cheap motor if they are on a budget, and if I have heard right the 1518 and 1520 is not available anymore??
I'll report any changes/problems that may arise during further "testing"
Thomas G