I fully understand Check Airman's point here.
I recently transitioned to the A320, as a Capt. Six of us transitioned from Boeings in the last 3 months.
Whilst in training, we were advised in one of the last sims (new instructor) to adopt this 'feet up' technique.
The company is now getting quite a few FOQAs on dragging brakes, probably from us.
Apparently, the pressure needed to raise a Level 2 FOQA is unnoticeable to the pilot.
Coming from 38 years of 'heals on the floor', it's a big ask to amend previous habit, though I personally was trying very hard to transition, and was mindful of steering inputs with heals not toes.
Our company has issued an FSO to clear up the stance on this.
Cutting a long story short, "...without delay" does not require the pilots feet on the brake pedals.
Now, fair enough for Airbus to make these statements, but it's folly to read too much into it.
I personally think there is a quite few risks with 'feet-up', such as inadvertent brake dragging, inadvertent disarming of AutoBrake in both a rejected TO and on Landing. In an Autobrake assisted abort, the brake will be symmetrical anyway, and I am not going to risk an inadvertent application of brake on a V1 cut.
Old dog, new trick. I personally can't guarantee that I won't revert to my learned habit of pushing with my toes when a situation catches me by surprise.
I'm going back to toes. Too old to change, and apparently not necessary.