The HV motors especially with the 5mm shaft are far superior to the feigao motors in terms of efficiency and quality, but if you really want to save money, get the 12xl and run it on 6s with the mmm. I'll tell you one thing however. If I could go back in time, I would definately buy a neu motor instead of the feigao I bought, even if the neu costed $150 more.
Check out my custom converted 8ight:
Sub 7lb, lowest CG of any 1/8 buggy