So far, I have had no issues updating site to #WordPress 3.6. All went very smoothly and I was pleased with the results. At the same time, I also updated an install of the #SHOPP e-commerce plugin from 1.2.5 to 1.2.8. While all appeared to go smoothly, I discovered that both the add-on and UPS shipping add-on directories had been removed. Of course, I was able to re-install the add-ons and my settings were still in the database so it wasn’t a huge issue. I don’t think the SHOPP auto-updater should have removed the directories.