ANY way you want to put it. 4" of stretch in a halyard is enough to make a sail ripple and not get full force out of it, Creating heel, and sideways movement when you want forward movement, be you a racer, or casual sailer.
XLS extra and extra T are the same, see here
with extra being a blue with different color tracers, T having white with other color tracers.
I would still recomend a combo, some sort of higher strength/less stretch line for the halyard.