How easy to read are small caps vs lower case?

I'm well aware that text in ALL CAPITALS is harder to read than text in lower case or mixed case, for whatever reason.

But what about Sᴍᴀʟʟ Cᴀᴘs? With a bit of Googling I can't find any references for the relative ease of readability of small caps. My intuition says Sᴍᴀʟʟ Cᴀᴘs would be easier to read than ALL CAPS but not quite as easy as mixed case... but I know well enough to not trust my intuition. So does anyone have any data or pointers?

Answers with sources and references preferred, but even just some pointers to useful discussion would be helpful.

[My specific context is more related to titles than to body text, for what it's worth, but titles that need to be readable from a good distance with a lot of other visual distraction nearby.]