I have heard some rumors about companies going to a 12 cal system - instead of the HRC 2 (8 cal) and HRC 4 (40 cal) which seem to be more widely used. Anyone else heard this?

It's not so much that people are going to 12 cal as it is that some are getting away from categories. This was actually discussed at the last IEEE 1584 meeting in February this year. 70E only requires that the arc rating is greater than or equal to the incident energy. The categories i.e. 1, 2, 3, etc. were a carry over from 70E's hazard risk system that was developed before calculations were more widely used. Cat 2 is 8 cal/cm^2 and many use it as a default level of protection.

I think as PPE becomes lighter and higher rated, you will see more people moving towards higher ratings if the garments are light and comfortable. 11 and 12 cal PPE is a step in that direction.