[dnanian]

There are a lot of different 'parts' to Spotlight. In general, Spotlight - that is, the process - should be on. Privacy tell spotlight to not touch the drive. It's different than the overall state of Spotlight.

It's best to use Privacy. They fixed the problems with privacy long ago (it used to vanish unexpectedly, hence the need for spotless originally), and I think you'll find it'll work fine as long as you're using Smart Update.