We have added this to IMLeagues and worked great with our first season. Before we would have to hunt down everyone, verify sizes, as the captains would normally just make the sizes up and then always had people trying to take shirts that weren't allocated to them.
Once we added it to IMLeagues, it prompted them the next time they logged in, we captured their sizes, and had less chaos than we ever had before with our last season.
You do have to export an report, but took maybe 2-3 minutes just asking simple Excel Filters and a counting formula for sizes. I'll gladly take on that extra few minutes than the headaches of handing out shirts and all the drama it use to bring.