As part of this discussion about what shorts to wear, i'll throw a twist into it.
My experience is that after the bike most people are ill-served by sitting down and taking their time in T2. Yes, your body may be kind of weary and both body and brain are urging you to give it a rest for a while, but to do so often exacts a toll on the rest of the race. Your muscles may like a break, but what they really do not want is to be activated again after sitting down for even a few minutes -- let alone time in double digits, which a lot of people take! My approach to an iron distance T2 is to take as little time there as possible while making certain that you have everything you need for the run.
With this in mind, then, if you plan to change into running shorts do so quickly and try to do so standing up. Better yet, though, is to take the next six weeks and get comfortable running in what you have just spent 112 miles biking in - which is what you also spent 2.4 miles swimming in. Keep it all simple, as there will be enough going on with your iron-addled

brain without adding to it a wardrobe change or two

!