As it is, it keeps us from scanning the AppDomain as well as the working directory. The only thing we continue scanning is FakeItEasy itself, which
1. hardly counts, and
2. I think maybe could be done away with (I was updating [my original comment](https://github.com/FakeItEasy/FakeItEasy/pull/251#issuecomment-33680912) as you were adding this one, so take another peek if you don't know what I'm talking about).

So I'd almost prefer `DisableExtensionScan`, if we are agreed that this is the right approach. I'm still a little worried about making a change and later wishing we'd implemented a more flexible Bootstrapper. Not that those two systems couldn't live together, but why not have one if we can?