Ah...my least favorite application of type is typing from afar...I want people to figure out their own types. Doesn't mean I never do but I'm not looking for a system. And I usually have to work with someone before I know for sure. By that time they've usually figured it out themselves...Personally, I think functional analysis is completely unnecessary, even though it may have merit. Primary functions are generally fairly obvious if you pick one definition of a function, and one way to split the populace into eight categories a la Jung--But they aren't as apparent/observable as ones type anyway. I see all functions but the first as potentially out of order, and when people contemplate them they base their conclusions on what their preconceived notions of function order are. I have been guilty of this myself, of course.
I think Keirsey's beautifully behavior-oriented.
And Kiersey--I kinda threw him away after his Please Understand Me remark, "The relative rarity of the ESTP's opposite on the Intuitive side, INFJ, means that shuch matings will be quite infrequent, as they should be." I"ve been married to an ESTP for decades, thank you, and it's been a whole lot of fun. Didn't like the stereotyping.