I have double-walled smokepipe on my stove due to clearance issues. It still gets very hot, so that you do not want to touch it sometimes.
My friend has single-wall pipe, but he noticed his tile wall behind the stovepipe was getting very hot, so that you could not touch the wall. Last night he set a piece of "unrolled" stovepipe on top of his stove, right behind the smokepipe (kind of a quick mock-up of the half-pipe heat shield you mentioned). The wall soon was much cooler.
I have often wondered if I'd get more heat into the room from single-wall pipe. However, it may be wiser to try to use heat tubes thru the stove, convection blowers, etc. to get the heat off the stove instead of off the smokepipe. I don't know.
Good question though. You don't see many single-wall pipe heat shields for sale. But I have to admit that the double-wall is a pain. Seems like all the accessories like barometric dampers, manual dampers, magic heaters, etc are single wall. And double wall is expensive, and you almost need a telescoping length to get to a wall thimble for horizontal runs. That is pricey too.