I store IPTC/XMP data in my images but not ICC.
Even if I accept PM only gives estimages. I don't really understand how can setting two stops below a size give almost 25-33% oversized files. It doesn't seem me an estimate. If I set 150 kb I would find acceptable to have some files say around 170 but most under 150. But all above 150, and most of them around 200?
I think this option should work limiting all file sizes to be maximum the set value. Or at least to have an option for working such a way. It is often that I have to start the same task sending my images again and again because I have file size limits and PM fails to produce the sizes it promisses.