Also, "free forever for open source" strikes me as problematic because of the above point: Isn't an open source product likely to prefer open source updating? Open source communities tend to get really sticky about apps installing things themselves and such, so this seems like a really iffy place to add a proprietary component.

That aside, I totally see a lot of room for more/better updating mechanics. There's two major culprits I find in a lot of large-scale apps, and I don't really like either of them. But then again... without knowing how Pakkly works, especially OS-specific install details, I'm not sure I'll like it either. ;)