Re the question of reducing equipment weight: here is where I have ended up. This may be far more than anyone else is interested in, but if anyone has reactions, I'd look forward to them.
I’m not posting about travel. I’m posting about age. My most common equipment set is about 11 pounds and off-center on my back because of a tripod, and I’m finding this less pleasant with each passing year.
After devoting perhaps far too much time to this, here are what I see as the options:
1. Smaller sensor: APS-C. To get a large weight reduction, you need a smaller sensor so that you can take advantage of smaller, lighter lenses. Unfortunately, most manufacturers don’t have a serious mirrorless APS-C line now. Canon, for example, now has a passable APS-C mirrorless camera, the R7, but only 2 APC-C F-mount (RF-S) lenses, and exactly zero high-end RF-S lenses.
The main exception (I might be giving short shrift to Sony) is Fuji. I would be very happy with a Fuji system if it weren’t for the X-trans sensor. Many Fuji shooters say that it’s no problem to process X-Trans raw files with Lightroom and ACR, but I’ve seen enough examples of problems and read enough by committed Fuji users that I'm convinced the problems are real. They don’t always appear; their presence and severity depends on things like colors and the amount of random fine detail. And they are generally small enough that they aren’t apparent online. However, I print relatively large, so it’s an issue for me. I’m not willing to give up Adobe because my entire workflow centers around it, and it would take me a huge amount of time to reach a similar level of proficiency and speed with new software.
There are work-arounds: a separate raw rendering program, Adobe’s Enhance Image, and various changes to sharpening. The first two I know work, at least to some degree. The third I’ve never seen documented with images. But this would be a complication, taking a little time and resulting in duplicate images.
2. Smaller sensor: Micro-four-thirds. Here the clear contender is the new OM Systems OM-1, which from all accounts is a superb camera and perhaps the best available in any sensor size in terms of relevant computational photography functions. There are a fair number of excellent MFT lenses. The larger DOF at any given aperture is a drawback for some people but an advantage for me, given what I do. It’s only 20 MP, but for static subjects, it will do sensor shifting to give you 50 MP raw files handheld and 80 MP on a tripod, which also reduces noise.
The main drawbacks are the weaker low-light performance, the limitation of 20 MP for images where the subject is moving, and the 12-bit rather than 14-bit captures. Peripherals are also less available; e.g., there are very few choices for flashes. This seems like it might be a step too far.
3. Just buy a FF mirrorless body and a walk-around lens designed for it—in my case, probably a Canon R6 Mark II and the RF 24-105 L f/4.0. This saves only 300 g with the walk-around zoom and only 200g when I use my other EF lenses and need the adapter. However, the combination of IBIS and in-lens IS is so good that I could usually leave the tripod at home, saving another 2000g (about 4.4 pounds).
The R6 has two of the computational tricks that the OM-1 has: you can tell it to save a bunch of captures in a burst from before and after you press the shutter. This is great for action photos of wildlife (not relevant for me) or kids (relevant for me). It does in camera focus bracketing, and while it doesn't create a composite raw in-camera, that is trivially easy for me to do in post. I don’t believe it has the ability to use sensor shifting to capture higher-resolution images, and it’s only a 24 MP sensor.
There are no backsies, as kids used to say in the US. These are expensive options, and whichever I do, I’ll be stuck with.