If they are running these boards at 314W DC/55v/5.6A for the HLG 350... that means you could get more out of 1 x QB648 by using a 200W driver. Yeah its not going to be as electrically efficient at lower wattages, but you're getting a lot more light by squeezing the white diodes from 77.77mA to 92.26mA. Those reds are rated at 700mA test current, which means if whites are run at 92.26mA, reds are running at only 553.6mA.
At these currents you are under half the maximum rated current for white, and only a little over a third the maximum rated current of red.
It's going to produce more heat at these currents... but not a shit-ton, and you're also getting a lot more red photons out of the red diodes.
I'd like to hear any arguments why this isn't better advice, when you can easily pick up a decent 200w driver for the price of a MW HLG?