Sorry for the slow response to this last update. Over the weekend I participated in Ludum Dare 19, which pretty much consumed all of my time. Now that it’s over, back to work.
Backpacks have been updated to support the full number of pages, should you choose to purchase them. For the sake of my bandwidth, profiles will only show as many pages as the highest placed item, so if you bought all slots but only use to page 6, it’ll look like you haven’t bought the upgrades on tf2stats. If that REALLY bother you, just toss an item on page 20.
A lot of new items were also added, which can be found here. Nothing too surprising really.
For those curious, the item token format in the API has changed slightly, to support larger backpacks. Changing your code to support this should be easy though.