Most definitely an amateur here as well, but a couple of things that I've noticed with cap irons is that they can be used to limit the depth of cut (I don't think the plane will cut any deeper than the chip iron is set above the edge of the iron), and Steve Knight doesn't put them on his planes. I recall Steve saying somewhere (but I can't find it now) that a tight mouth eliminates the need for a chipbreaker. Of course, his irons are 1/4" thick.

David