I am an Airbus Training Captain and have observed numerous techniques in this department. The first thing to say to ex-Boeing pilots is that you are no longer flying a Boeing! If I ever fly a Boeing the first thing I will do is ditch all my Airbus techniques, then find out how Boeing pilots with considerable experience on type do it - I will then emulate them. I would suggest to you that is pretty good advice for coming onto the Airbus. Therefore the advice of people like Fantom strikes me as probably worth listening to, rather than some 'good ideas' you have from previous types. No one really cares how you did it on a Boeing or on an MD-80 or on a Tristar or anything else. Old dogs can learn new tricks and there are a lot of new tricks to learn!
In terms of what is written down, this is what the good book says in the Airbus FCTM (July 2008) Normal Operations Pre Start P15/16:
"The rudder pedals must then be adjusted to ensure the pilot can achieve both full rudder pedal displacement and full braking simultaneously on the same side. The armrest and the rudder pedals have position indicators. These positions should be noted and set accordingly for each flight."
I would suggest that to achieve full rudder pedal displacement and full braking simultaneously on one side requires that your feet are off the floor and on the pedals. It is therefore implicit in that statement that you should operate with your feet off the floor and on the pedals. The vast majority of experienced Airbus pilots follow that technique. My own observations of training and debriefing following unsatisfactory crosswind landings or take-offs have invariably found that those who have difficulty maintaining the cenreline are those who put their heels on the floor. That is not to say that this was the only issue, but I rarely see anyone who has their feet up in the manner so well described by others here having directional control issues. When in Rome do as the Romans do........