Yes, I agree completely.

This classification is (aims to be) "hardware"-oriented; the three groups should be supported by different sets of hormones. (I am not a biologist, I merely copy the info from other sources; mostly the Married Man Sex Life blog. The author is a nurse, so I trust his expertise.) I can imagine that the same "hardware" foundation could be used to implement multiple different "software" emotional flavors in the brain.

Actually, I believe there might be even some cultural variations; if nothing else, the mere belief that some two emotions should go together, or that some emotion should be felt in some situation, would create a cultural difference.