Extra Load tyres have a stronger construction to allow for higher pressures inside of the tyre to support more weight. Put simply, you can make the ballon take more weight by putting more air in it. You don’t have to put that “more air” into it. Run an XL tyre at the normal “standard load” pressures for the car and you are very unlikely to notice any difference.
I was under the impression that xl tyres are unnecessary for such a light car? The ability to carry extra load comes from additional reinforcement which will no doubt make them a bit heavier, tougher and therefore slightly less comfortable and compliant?
Slightly less yes but also more responsive particularly when steering and loading up into a corner. Also more road feedback which is good when pushing the car