Gary,
Astro Pixel Processor is pretty new so I doubt you'll find anybody with much experience yet. I have watched a couple of the videos and will have a play with the trial when I get some time.
From what I have seen it has a more limited set of options than PI which may suit those who find PI has too many
It still looks more complex than CCDStack which is my benchmark for ease of use.
I'll report back if I get a chance to try APP...
Cheers,
Rick.