[magman]

First, welcome! In using a low kv motor, higher voltage set up you will gain some efficiency, but more importantly, your components will run cooler...more efficiently. I have a mbx-5 that I run on 4+5s and the 5s set up is more efficient and the components run cooler. On 5s, I turn my EPA throttle adjustment down quite a bit.

In answer to your second question, it sounds like a minor glitch in the programming. I could be wrong see it as I know nothing about quark controllers.