Having not flown any aircraft approved for any kind of derated thrust during take off I can still agree on that it might be wise not to change the configuration of the aircraft as well as treating the remaining engine with a little extra care.
But on the other hand the engines are certified and approved for running at t/o thrust for a certain time (in my case 10 mins when single engine - this might be the common rule) meaning that there really shouldn't be anything to worry about. In addition to this one must also consider the reason for say an engine failure and depending on the conclusion drawn it may very well be a good idea to set max thrust on the remaining engine in order to get as far from the ground as possible before the it quits too (fuel filter by pass on the running engine - contaminated fuel).
What it all boils down to - as usual - is that it is up to the captain/crew depending on the specific conditions for every specific scenario. It is impossible to say that either of the procedures is always right (or always wrong). I can recall a number of accidents where aircraft have been lost, both due to the crew not selecting max thrust when needed to and in some cases when they have killed the remaining engine by doing it.
As always, fly the aircraft and don't just do stuff without thinking first. Even though a V1 cut is about as bad as it can get it's what we all have been trained for and what the airplane has been built to do (with some safety margins too) and it's not about split second decisions. I absolutely agree on that you should engage a/p asap, if the conditions permit, in order to free capacity so that both crew members can start to evaluate the situation properly.