Going from wide to narrow (er) tires

why would you want to go narrower than a 2.3? At this point, that's a gravel or pavement tire.

I think hardtails, especially, do well with wider tires like 2.6" to 3.0" wide. It's partly a comfort thing, but the big deal is that with more rubber deformation, you get more traction because the bike bounces off of stuff a little less. The narrower your tire, the less rubber there is to deform around roots/rocks, the more the bike is going to bounce off of stuff on the trails, and the sketchier the ride will be.

There are some folks who rode 3.0" tires for a long time and went narrower. I was riding a fatbike for several years and then "sized down" to a bike with 29x2.6" wheels/tires. You do get more supportive tires when you get narrower. This matters when pushing the bike hard into the corners. Too much tire deformation and the handling can get vague. Riding style seems to be a major component to this. The bigger the tire, the more exaggerated this can be. Another detraction from big tires is that they can bounce like a ball pretty easily under certain conditions. High speed, repetitively chattery type stuff. That's why I sold my fatbike. Fatbikes do great when going slow over nasty terrain. They're not bad when it's fast and fairly smooth. Fast and chattery - terrifying for me as the undamped bounce from the tires became a feedback loop.

I find 2.6" tires to be a bit of a happy medium where I have some extra volume to give a bit more deformation. But tires are still pretty supportive, at least if I buy tires with the heavier duty sidewall options. A friend of mine hasn't had good things to say about the 2.6" tires with supple xc sidewalls on our trails.

Way back k in the Early Years of the MTB, the same discussion was waged over tire widths, and what was optimal, what was too much...
Weight, especially 'rotating mass', was considered of vital importance then, as efficiency and longer, endurance-type rides were kind of the norm at least where I am. Tires galore stocked all the shops, and within a couple years I had hundreds of lightly used tires in my garage.
A typical arguement from a shop owner in favor of narrower tires was something like, "Are you really OK pushing around that 2.5" 700 g. tire up front?" While that made for a helluva good hypnotic subliminal that he didn't even know he was using, I really didn't think it was all that much, and blasting down the sketchy descents we made, I felt a whole lot faster than the guys who bought into the skinnier thinner lighter mantra.
Switching to some skinny mythos tires for a few months contributed to a ditch jump-gone-bad that broke my leg in more places than my surgeon could count.
So, Adam, I'd just say, ride what feels good to you.

A few months ago I went from 2.6's front and rear to 2.5 fronts and 2.4 rears. We have a lot of mixed surfaces here, so good cornering spikes up front and good braking bars out back are a necessity. I have had good success with Minion DHF's up front in 2.5 (980ish grams) and Dissector (915ish grams) or even Rekon 2.4 (840ish grams) on the rear on both the TB4 and ARC. These are not race bikes, but rather trail bikes that I like ride as fast as possible everywhere. I don't like to walk anything either so climbing efficiency is super important. The switch to the smaller tires took about 1/2 pound of rotating unsuspended weight off the TB4, which was never a good climbing bike, and on the HT ARC, which was already a good climber, made it so much better. Dropping tech isn't a problem with any of these tires either. Just say'n!