Has anyone used this recipe before and can vouch for it?
I live in Europe and marshmallows are a hard to find commodity (and if I can find them they're outrageously priced).
I've never tried this recipe because I'm pretty sure it wouldn't hold together for covering a large cake. I mean, can you imagine picking up an 18-20" (45-50cm) circle of buttercream and expecting it to remain intact while you position it on a cake? There's an excellent non-marshmallow recipe here in the recipe section called Michele Foster's fondant. When I make my own fondant (not often, I'll grant you, but still), this is my go-to recipe. I like the original version better than the updated one, but that's just personal preference. I don't like to use marshmallow fondants here in Mexico, because marshmallows are made differently here and the fondant tends to come out wonky. Hope this helps!
There are 327 reviews on that site for that fondant. I haven't read them all, but here is a link.
I've tried it. It tastes really really really good, but it's really difficult to work with. Lots of "elephant skin" and other problems. Small cakes (8" round or less) was hard enough I can't imagine a big cake.