True you can use a Flow with 1s. You just won't see any more voltage to the receiver and servo than what the battery is supplying because there is no built-in booster for the BEC. I used a SXX Stock Spec with Flow board (booster removed) and no outboard booster or rx pack for a year in 1/12th scale. Worked flawlessly for me. Servo could have been a bit faster, but otherwise perfect operation.