Adding the options page(s) in WP always feels a bit awkward to me. Perhaps I need to study it more? That said, this solution sounds very interesting to me. But I have some questions if you don't mind:
1) Can it be used along with the WordPress transients API? Wouldn't that make it even faster? Or is Fast just referencing the setup process?
2) Maybe it's just me but I'm not familiar with YAML. Why not XML? If there's an advantage to YAML perhaps it would be good to list that as part of your features? That is, not just features but benefits too?
3) Can this also be used for plugins?
4) The (green button) View Pricing licensing confuses me a bit.
"-Unlimited sites, servers
- Personal License
- Commercial use allowed"
So can I or can't I use Fastoptions in themes that I might distribute? What about the same for plugins? Does it make a difference if the themes or plugins are free vs being sold? Please clarify.
Note: My main interest is plugins and not so much themes. Being able to quickly and easily add options would be uber helpful. Mostly that's for clients/projects but sometimes I'd like to be able let a plugin loose "into the wild" (so to speak). If the license doesn't allow for that then this might not be the best solution for me.
5) If it doesn't work for plugins, might you consider doing a version that's WP plugin dev-centric?