Well, while I was rendering a test image with IES lights, suddenly max shut down. It was after 2 o 3 hours of testing and I didn't change anything in particular to cause an error. I can't know which error cause the shut down. Opening an autoback I got huge IES web in viewport: I had 2 standard corona rectangular lights with no IES and opening the autoback the IES file was added to this lights.
While choosing IES file I get weird results like a totally white render, even at super low multiplier. I know these file are right because with other render engine they render normally.
I also noticed that get clean reflective material is really really difficult with CoronaLights. I let render a region to a quite high render pass to see if I can get out of noise, but even at pass 1725 after 6,5 minutes it's not clean, with some rough math it means that to render a 1280x720 I have to wait for about 2,38 hours, and for an image twice bigger about 9,5 hours. Render settings are almost the default, PT+PT 4 samples and lights samples multiplier at 10, last build.