OK, I bought it (in fact the wife got it for me, so I've to wait till she gets back home).
Yes, I expect it to be great for macro works. In fact, it's the main reason why I bought it, the second being that my GAS strategy is to buy things I really need. In this case, I know there are several shots I did not do because I could not do the setup as needed, so this tool might help.
I don't think it'll be OK for a WLF though, but I'm eager to see the 1.25 magnification factor.