Combo or combination-type refers to the type of arcs that it can detect, either series arcs or parallel arcs.
I would agree to disagree on this point. We test GFCI breakers and outlets because they’re a safety item. AFCIs are in the same category. No problem explaining that to a seller who has to reset their computer themselves. Same thing happens when the power goes out.
We all have to decide what works for us. I have no problem with someone else not wanting to test them. I do it because I decided to test them.
Why not trip all of the standard breakers and the main too then? Those are also safety devices.
I limit AFCI testing to new construction and unoccupied houses. I advise my clients to test them all at move-in and again whenever they adjust clocks for DST.
That works too.