I've never used one, but asymmetrical angles aside, I think of them the same way that I think of knives. Fixed blades are arguably better, but folders are just way more practical. Personally, I always close the razor to set it down. I suppose one could just set the kamisori on the counter or a washcloth, but it would feel weird to me.
Of course, none of my kitchen knives are folders, so there is that.