which feigao?

The 5700 under load on 3S lipo will be fine. Even the guys at Castle will support this configuration. The 5700 can also stand some gearing. If you know that you will be going 4S, then get the 4600. Just keep in mind that when you run any motor on the edge of its rpm limits, it will get hot.

Either way, the 4600 on 3S for good fast running and 4S for insane; or the 5700 on 2S for good fast running and 3S for insane. Just remember that if you go with the 4600 on 4S, you'll have to use an external bec. I'd just use an external bec regardless. It will help to keep the esc cooler.