Hmm I am not relating to this concept of merging as an end point for nine. It's certainly not something I strive for or desire. It's an almost inevitable happening when other people are around. Often times, I know what I want when there is no one else around. As soon as you add a person to the mix, it's like *poof* I lost the ability to think for myself. I am keenly aware of and constantly thinking of that other person and what they need or want. In fact, even though I don't always know what to do when no one else is around, I am always aware of what I could do or what I might like to do. When I had children (over 20 years ago now), it was of course no longer easy to balance that, and I think up until that point, I did not realize how much tension there could be when what others needed conflicted with the boundaries of one's stamina. Now, of course children need you and there are no options, you are going to get up in the middle of the night, you're going to take care of them even if you are ill, but somehow that opened my eyes to the level of merging? Because it ventured into the uncomfortable zone of "Hey, my needs are totally being obliterated here" rather than the easier to not-notice blending into other people's desires and wants.
So, merging is not an end-point, it's more of a foregone conclusion. It's not accompanied with the intense and craved-for feelings of sx-merging, it's more like a void, a black hole. It's the waking up, the being present to oneself in the here and now that's the destination for 9's, the liberation that your voice matters.
eta: That's not to say that in the merging, making the other person happy, you don't feel happy that they're happy. You do. It's just that, you released something to make that happen rather than blend it, and sometimes you aren't even aware of what you let go.