I too am also still waiting on 20 x pmma lens 5mm from Ali Express 
I fear a trade war between US and China has my order siting in a container ship somewhere.
I have been able to take tiled picture sets and use Microsoft Image Composite Editor to stitch them together on the lower resolution optics, my understanding is that this PMMA lens will help add to the contrast and potentially have better quality stitched together pictures. The white LED alone seems to have been enough to lighten the picture. I am really curious if I am even missing out on some quality without this lens.
Given that we now seem to have a supply chain problem with the PMMA objective lenses, I am interested in finding an alternative. Adafruit has much larger 40mm lenses that just seems crazy big. Perhaps 2 LEDs and/or a wider hole?