If Dwellers references that "sense of the All" thing, it's probably alluding to Diane Duane's books, not the TMP novelization.
I remember we were talking about concepts labelled the All, the Others, and the Other. I'm very keen to get the concepts straight, and I do a number of things in order to aid my memory, because sometimes I don't recall things as well as I would like. I've tried to take notes and index content in the books so that I can relocate an important passage; some of my indexing is guesses about what will be important in later books. When I hit on something that sounds familiar in books down the line, I check back with my notes and index, and there have been a couple of things I've added here and there.
Out of Diane Duane's contributions, I've read The Wounded Sky and My Enemy, My Ally so far. I don't remember details from those books about the Vulcan sensory perception of a higher power called the All though, I'm sorry to say. My memory is very bad though, I admit that's definitely true; it's why I'm using additional strategies to keep the little details straight and help keep track of how the picture builds from book to book.
This idea of the Vulcans being able to perceive a higher power or force that is what brought the universe into existence fascinates me, and I would love to pin down references in the Duane novels, and index them for referral, to keep them fresh in my mind. I'm glad I've marked the passages I have for The Wounded Sky, because as beautifully as I find that book to be, trying to find a passage blind without using my index is difficult; so many of the gems are scattered about in the prose.
If I had to guess, Vulcan perception of the All somehow didn't grab me when I read through The Wounded Sky and My Enemy, My Ally and then subsequently seized hold of me when I was reading Dwellers and skimming around in TMP novelization. I was skimming through TMP extensively to familiarize myself with what its says about Deltans so that I could compare and contrast that with what Dwellers says about Deltans, and I stumbled on the footnote on pages 126-127 of the paperback copy I have, where Spock is meditating on the V'Ger presence and searching for the mental connection with it.
At the back of my mind was Diane Duane mentioning that she had read several of the novel series in her interview for the Voyages of Imagination book. I imagine that the novelization was a pretty important book, being the only way to revisit the events of the first movie. I believe you when you say that Dwellers might have drawn from Duane's books for the Vulcan perception of the All...but I thought that Duane might have drawn the idea from TMP, the only way to re-experience TMP for years and years.
I don't remember reference to the All in TWS or ME, MA. I do remember material in TWS having to do with the Others, which Dwellers brought me back to, so I made sure to index a passage having to do with them. Dwellers refers to two separate higher powers, the All and the Others, which I thought was an interesting detail. I also remember you mentioned that Spock's World explores the same or similar concept, but calls it the Other (singular rather than plural), so I included that in my notes, so I can keep an eye out for it when I reach that book and read through it.
I assumed that Dwellers was mentioning the All because it differentiates two different things; and also because Dwellers has a lot of other stuff from TMP, but specifically stuff only found in the book version of TMP. It's using the same word, the All rather than the Others or the Other. I don't remember it being elaborated on as a presence that Vulcans sense in TWS and ME, MA.
Very honestly, hat in hand, I hope this doesn't seem argumentative, or pedantic.
I would be very happy to share what I've indexed; I know this is getting into very OCD territory, but if it is helpful for others as it is helpful for me, then hopefully no one will think it's content too dry to post. What I've indexed though is page numbers specific to the mass market paperback editions, it wouldn't be as helpful for hardcover or kindle editions. It may be OCD, but for me it's just to help me keep details straight.