Which is better? (mega/feigao)

[DrKnow65]

Tig welding (soooo jelous, I know how, but have no access to one now that I live in Colorado :(

The ubec will put out more amps without dropping in voltage like the internal bec, so your servo's and fan will perform better even on 3S. Also the internal bec is set to 5v and the ubec is adjustable (via the caslt link-not the usb cable for your mm- castle link) so you can set it to 6v, or I like 6.2v because when you load it down it sets right a 6v...
So when you see the servo spec's at 5 and 6v you get an idea of the difference in performance. The ubec will help some with the ESC temps even on 3S, and alot more on 4S (BrianG has done some tests on the performance/heat of the internal bec, you can find it if you do some searching of his posts/threads).

Glad you found a problem (with the settings). I'd still highly recoment the taller pinion gears though, you'll notice a big difference, that mega is a torque monster.