I think it all comes down to how much power your setup needs. My RC10 weighs 1.5 kg RTR and pulls about 300 Watts peak with current gearing. At 11.1V, 300 Watts is well within the limits of the Jazz 40-6-18. It barely gets warm right now.

Next week when I run 6S I will do the runs with my DPR attached to record power levels. I will be using larger rear wheels and smaller gearing, but in total the top speed will still be about double, so power should shoot up to 700 Watts or more. On 6S that is still well within the limits of this Jazz so it should be fine, but we will see what happens. TBH I am more worried about my little RC10 gearbox handling the speed.

In theory the Jazz 40-6-18 should be good for over 800 Watts continuous.