That’s a very interesting list. Glock is by far the most popular weapon of choice. I’ve shot a Glock 19 and I liked it. The trigger is fantastic. Much different than the XD.
So I can see why it is the most used for IDPA.
There are some improved triggers you can get for the XD.
http://shop.powderriverprecision.net/category.sc;jsessionid=89AD9A0064BB93B14CA916195319C455.qscstrfrnt05?categoryId=3