Both systems are good, just depends on how much power you want!!?? The Mamba max pretty much doesn't have a limit, and now there is a 9000Kv motor!!!! The Sidewinder system is limited to the 5700Kv motor, which is still a pretty sick system, and what a good price. So if you want unlimited choice of motor, then the Mamba is a better choice, however more power=more spending, you will need better batteries, etc... Where if you stick with the Sidewinder with either motors you can keep your current batteries and it will work fine.
Once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return - Leonardo da Vinci