As moronic as the move was, when I took it out of the freezer only about 1cm depth had frozen, but had done so solidly. I tasted it, and it had a really nice mouthfeel to it. The creamyiness really stood up well to freezing, which amazed me because it was half fat creme fraiche to begin with. I liked the tang as well.
I don't have an ice cream maker and the freezer is literally smaller than a shoebox, so I won't be experimenting any time soon. But if you're into your ice creams, I'd say it was definately worth a go using it as a base. A quick google search shows it's not unheard of, but all the recipes seem to dull it down with milk and egg yolks so you only get a bit of the tang in otherwise normal ice cream. This had a particular sort of smoothness to it that seemed worth retaining. I could see it working as a start of either a savoury ice cream or sweet. Something with herbs possibly? Strawberry and balsamic? I've paired creme fraiche with mint before and it worked well, so maybe there's a twist on that.
If anyone has a go, or indeed has tried something like this, I'd be interested to know the outcome.