gilly is indeed an ENTp (prolly Ne sub) 7w6 so/sx in my opinion (I know he thinks he's sx/so, but he simply doesn't match the descriptions of that type that I have read). Allie, an Ne-ENTp, shares the same enneagram and instinct stacking.
sx/so: "This is the type that exudes the most raw charisma and sexual energy. They may identify so strongly with whatever they're involved with that they often become the symbol of its core essence, and sometimes its lead agent for change."
so/sx: "This type has very strong one to one social skills, but is usually uncomfortable in group settings. They enjoy cultivating multiple relationships, and can be intensely involved when in the presence of someone they are interested in, but have difficulty sustaining these bonds when apart. This may give the impression of being flighty and rootless, willing to adapt and mirror others in order to connect, but lacking a defined approach that would give their relationships a more solid standing."
Now, I don't know Gilly well enough to say definitively that he is the latter, but I can say such with Allie. Gilly doesn't seem intense enough to be sx/so, but like I said, I could be wrong.
another interesting thing: the so/sx description seems to match the general nature of 7w6 EP's - it's more laid-back and spontaneous. The sx/so description seems to correlate more with 7w8 P-sub ENxj's, as it illustrates a much more intense and, to some degree, direction-oriented personality (direction being due to their vision and desire to implement).