If you aren't going to be racing and speed is the main concern, it's mamba max all the way.

I'd go with the 4600 system. With that you could go from mild to wild just by switching battery packs. On 2S lipo, it would be nice and sedate with long runtimes. On 3S, it will start to wake up. On 4S it will be insane.

I used to run an RC10T4 with a MM 7700 system on 3S lipo and easily got over 60 mph. The 4600 system on 4S lipo would be faster. The 5700 system is fast too on 3S lipo. It can stand gearing much better than my system could. My first choice would be the 4600, followed by the 5700 system.

I'd only go for the 7700 system if you are going to limit yourself to 6 cells or 2S lipo. Running the system on 3S was a PITA.