The boys over on the NACHI group (home inspectors) seem to be saying AFCIs run 5-10 degrees hotter than the regular breakers read with an IR thermometer. I think that may just be anecdotal but it is worth a look by a NRTL when you have a panel full. I doubt the electronics are good for much more than 70c (the typical non-milspec rating) and that is junction temp, not the outside of the CB case.
