The weather gods finally let me have a chance to use the APM 2" AmicI prism. I compared it against an Astro Tech 2" dielectric (99&) diagonal using my APM 152mm f7.9 scope. I had wanted to use my Williams Optics 66mm f6 but that scope has SCT threads on the drawtube and will focus only with a WO 2" diagonal using a SCT nose piece. The scope doesn't have enough in travel using a SCT to 2" adapter to focus using any 2" diagonal. The TBM 40mm Paragon and 24mm Pan almost come to focus but need just a few more mm of in travel. It doesn't have enough out travel to focus with a 1-1/4 diagonal either. Using a 1-1/4" diagonal, you can hold the eyepiece about an inch out of the diagonal to focus the image with the drawtube racked all the way out. The focuser has 60mm total travel so go figure. Anyway here are my first impressions of the APM diagonal.
Sirius - Yes there is a spike, but it is not too objectionable in my opinion. No added color noted from the APM up to 300x.
Jupiter - The spike is there but fainter and wider than on Sirius. The spike is the width of the planet's disk. Both diagonals showed the same amount of detail at 200x but the sky background appeared darker in the APM.
Moon - The APM appeared to give an ever so slightly sharper image than the AT diagonal. There was no color along the edge of the disk in the APM at 150x and again the sky background appeared darker. The WO scope will show a trace of purple at higher magnification with a dielectric diagonal as it was marketed as a "semi-apo" at the time, however you want to define that term.
Pleiades - The APM was slightly better than the AT at 30x, darker sky background and sharper stars. Higher magnification wasn't used as I wanted to frame the entire group.
Orion Nebula - Again, I preferred the APM over the AT. Low power, better contrast; high power, slightly sharper stars in the trap at 100x.
Overall, I'm happy with the APM for the use I intended, the Moon and deep sky plus terrestrial if I can somehow adapt the WO 66mm to focus using a "normal" 2" diagonal. I need to spend some more time with the APM for further evaluation but my initial impression is I'm liking it. The dreaded "spike" is only apparent on bright stars and planets. The Moon is so bright that it overwhelms the spike and it isn't seen. I attribute the darker background and shaper image in the APM as the result of less scatter. The APM does require 5-6mm of additional in travel of the focuser versus the AT diagonal.