I was preparing to create my top 25 OpenSearch plugins manually (less popular plugins at addons.mozilla.org often lack autocomplete and have other quality issues). Glad I read this before wasting 2 hours of my life.
Now I'm just switching back to Chrome. Does Mozilla actually expect site owners to create search extensions for ~5% Firefox users (of which in turn ~5% will actively install such an extension)? Firefox performance has come a long way, but Chrome is still way more polished. Apparently, Chrome is at the same time more poweruser-friendly, which really irritates me.