Talk:Search Service
Personally, I would prefer replacing the Search Plugins with Smart Bookmarks. There are quite a few extensions out there (ie. SmartSearch and Search Type B) that can be combined to completely replace the Search Plugins and they could be integrated to Firefox instead of having to write a lot of code.
The reason I prefer Smart Bookmarks is because they are quite a few users out there that are using this feature: We need to support them. The other reason is because the customization is already implemented. All we need to do is to rename the feature into Search Bookmarks and implemented a dialogue that is tailored towards that purpose (ie. instead of "Keyword" we can try "Nickname"). Lastly, there are a few other browsers with the same feature (ie. Epiphany) and it would be nice if we could import their Smart Bookmarks.