I can kind of see what you're saying here, at least with 5w6's because very few people seem to identify with the subtype and because it seems less specific than 6w5 or 5w4. But what do you actually think is the mechanism for this problem? Is it the descriptions, indicating a failure to misunderstand the wing, or is it actually an organizational problem within the theory? I'd also like to hear why you think the same of the 9w1, as I only somewhat agree with your assessment there.
My problem with Enneagram theory is the conventional understanding of instinctual subtypes. People seem to treat them as a separate base-three personality system without really connecting it to Enneagram, to the point that they describe each subtype as having extremely distinct behaviors and rigid traits. A common description for sp/so, for example, will look just like a phobic 6 description, while an so/sx description may look exactly like an 8 description. I wish people would integrate the subtypes into their understanding of Enneagram in order to better understand how they filter the instincts that manifest in each type. For example, an sp 6 should be very different from an sp 2, because the self-preservation instinct is influencing the behavior of very different types. For an sp/so 6 (such as myself), the 6's needs that are concerned with the self come first, and then the 6's needs that are concerned with larger social order and convention. An sp/so 2 by contrast will focus on the self-preserving 2 needs (which differ greatly from that of the 6), and then of the socially-oriented 2 needs. This is something I wish got a lot more attention.
What you are discussing here is actually very interesting. I just made a website for putting out my theories around this. So you are a 6w5 sp/so. In myers briggs, you are probaby an infp or a intp, am I right in that?
I find if you go to the library, many of the staff will be 5w6's and usually intp's. The N makes them somewhat creative, but it isn't a strong constant driving force in their psyche. The advantage a 5w6 has over a 5w4 is that they are not inherently anti-authoriatarian, and they need less change in their nevironment, they can do the same thing over and over. But they are also less "hippie-ish" and more down to earth.
The reason a 5w6 isn't a "true" subtype is that they don't carry the nervous, everchanging energy of the 6. "Nervous" sounds bad and it can be bad at low psychological health, but it can also be a very good. It's a right brain half funtion. Inspiriation, ideas, intuition, creativity. 6's are inherently sensitive and lack that outside filter (toward the rest of the world) other types have, 8's having the strongest, thickest.
Simply put, 5w6's are one of the most left brain halved, down to earth peole you will meet. They are very cerebral, but they are very level and there aren't too much fluctuations going on in there. They score very well on IQ tests but aren't necessarily "creative". On s higher level, they don't have the right brain halv activity that comes with being a secondary 6.
9w1's. 9w1's have, just like the 9w8, every trait of the 9. But they lack that agression, dominance, anger kind of thinking. Also they don't do to many power plays, their aim isn't go gain power, in work or relationships. They just want harmony. They are pure 9's.
Do 9w1's have that DRIVE of 1's? Some are fairly driven actually but the two laziest people I know are 9w1's. They are 26 and they almost never had a job, still live at home. Actually I got a cousin in Canada who's a 9w1 and he's almost 30 and it's the same deal with him. 9w1's do not have that DRIVE, that activity, that 1's posess, not even in diminished format. Also they aren't perfectionists or have some of the other common mental problems that comes with being a 1.
So I belive it's a theory problem. I believe the enneagram is an AMAZING depiction of reality, of humans. But you see, every tiem something if PERFECT i get suspicious. You how you find out the happiest familly in the neighbourhood with the perfect garden was actually molesting their children? I don't believe in perfection, I believe in reality wihch is infinety complex.
The current model of the enneagram is a mind blowng, mind expanding, mind breakingngly good description of that reality. I just believe there are tow minor flaws, and they are the fact that the 9w1 and the 5w6 aren't "true" subtypes because they don't carry that traits of their secondary wing in diminished form.
Think of all the people you know or have met, and compare what I say to them.