Didn't get a chance to really mess with these things until this morning.
On the plus side, it definitely works as intended. You'll notice the stepped pieces give you height adjustment as you move in and out. I'm not quite sure yet if it's going to be quite enough for me, but it gives me something to work with.
On the minus side, the two stepped pieces are held together with one small screw. Nothing is cheap plastic, it all seems fairly sturdy, but it's the sort of thing I get concerned about flying off. Probably nothing to that concern though.