Over the years I've used the take over pb in the flare maybe 10 times and never noticed a lag, but I think in the very dynamic situation of the flare, with not knowing what is happening on the other stick, it would be very difficult (impossible?) to tell if there is a lag.
Using thrust to cushion a potential heavy landing may work if timed just right, but really is not a wise thing to try. The reason being that if the thrust levers are not at idle the ground spoilers do not come up when the aircraft touches down, which can then result in a higher bounce, then if the thrust levers are set to idle just after the bounce the ground spoilers will deploy as there is a slight lag in the on ground to airborne sensing. If the ground spoilers do deploy when airborne a very heavy arrival on terra firma will result, as has happened in at least one airline I have heard of
In the flare, if you need to take over, TOGA 10 is the best option.... least likely to result in addition engineering checks, and a chat with the management
