I've run into a couple issues:
- Installing 3.13 overwrites 3.12 (by default), but does not uninstall it. (FYI: No version has uninstalled the previous [I start with v3.10ish] - using an upgrade code can allow this to happen seamlessly)
- There's no entry to uninstall 3.13 in the add/remove programs (since this is now using NullSoft instead of MSI, that's not surprising). There should at least be an icon in the program group to uninstall.