Samsies
Ne + So 9 = Pretty dang upbeat and bouncy on the surface, esp if excited. Social 9s can easily mistype as 7s (in other words consider your instinct stacking as well).
That said, my least favourite writers based on the 9 stuff are Riso and Hudson. Palmer and Maitri give a better take on 9 imo.
I created my "Whoa... what if I'm 9 not 7 =O" thread a few years ago and based on the 'upbeat' image I had, maybe the hyperness people saw the strong reaction was that I was a 7, but once seen it cannot be unseen. It's a very different kind of avoidance, 9s slow down, tread water as moving against something feels like it can create conflict, we are low energy (even if we are active), yet moving with something we do not want is unacceptable so we get stubborn and stop, kinda like a donkey

. 7s on the other hand speed up with distractions, they get active, they are high energy (even if lazy).
Other distinctions to consider are Id v Ego. All the talk about ENTPs being prone to narcissism always shat me because I am so not egotistical, I see now that it comes from ENTPs typically being Id types. 9s tend to be humble and unassuming without drawing attention to it, if you can see everyone else's view as valid in its own right, and are unsure what your stance is so dismiss your own in favour of those who seem to care more, it's tough to put up a front and tell people you're all that. We may not put others first, but we can often put ourselves second.
Anxiety issues v anger issues, of course 9s can struggle to see their anger so that one takes time and observation. I'm a head type only in the way that I am always in my head, I don't do anxiety though, I
can shut my thoughts off and just be in the moment.
There is always anger there, for me, I just don't show it, it is the most consistent emotion I experience, the cause of anger for 9s is generally feeling overlooked or easily dismissed/discounted which is something we create ourselves unless aware so it is tough to work past. Getting in touch with that anger is the hardest thing for a 9 though as we don't recognise it, our avoidance pushes our attention away from discomfort, before I realised I was a 9 I would have told you I was never angry.
I wouldn't say phobic/counterphobic, it's more a matter of w8 active anger v w1 critical anger. The counter-9 type is typically viewed as the So dom.