Can't speak to the XDs, Nathan, but I just bought an XD Mod.2 in 9mm and I can get all three fingers on with the 13 round mag, BUT, and it's a big "but", I have quite small hands and short fingers! If you're familiar with golf gloves, I wear a "Cadet" size glove. My guess is that most men and some women will struggle to get that pinky on the grip.
Springfield's specs show the XDs as having an even shorter height than the XD Mod.2, so I imagine it would be even more difficult to get 'em all on with it!