You've got USB3 builtin and a SSD drive, so those are the biggest things. As to deciding between the 80mp and the 100mp, I'd push you in the direction of the 100mp. The file size difference isn't that much, but the slightly higher base ISO is kind of nice, and if you want to really push things.
Actual file size difference will be based on the images, but I just checked the DT reference shots (EIPs) with both the 100mp and 80mp and they're about 116mb and 72mb respectively.
Keep in mind that the 2016 MBP is going to have the dongle fun to get a USB3 jack, so if you go that route have a spare adapter ready. Go with the XF with power sharing, plus turning off charging on the back and you should be fine.