Thanks for this, Aaron. It does actually look like Redis may be better
suited to our needs. I had originally discounted Redis because I had
the impression that it had volatile storage only, but now I see that
not to be the case.

Thanks again!
Yup, you've got Append Only, foreground  Snap Shot and background snapshot in there.

I strongly recommend following the Redis creator on Twitter if you start playing with it, is a pretty fast moving project at times