I run mine parallel all the time with the Eco on. One will run a little harder than the other but hardly noticeable. I will shut eEco off if wife is using micro where it is on and off on and off like on a power level. I will also shut it off when running AC.
04 Mandalay 40B, 2014 Jeep Unlimited toad, Aladdin tow bar, Roadmaster 9160 braking system.