FYI, they make an Affinity 20ga compact with a shorter stock and 24" barrel - you can then upgrade to a larger/adult sized stock. They make the compact in black and real-tree, so you may also be able to simply order a full-size 20ga Affinity with a 24" barrel.

I personally prefer a 24" barrel, which is noticeably shorter and lighter than a 28" barrel without any loss in down-range accuracy.