Jon, I agree. Made the decision for 12" max for my Dobs & 120mm for apo refractors (10" in theory for SCTs).
But its a freeing decision. Because concentration on quality for chosen sizes can then go into your choices. And also decision on mounts size etc.
The same applies to many consumer choices for any article really, where restraint or limit gas been established. Buying my F6 10" was an example, high grade mirror, less aperture, but hopefully top performance for the size.
For me, it's really a question of opportunity. I bought the 16 inch because the price was right and I built it into a scope that is both portable and potent. It definitely shows more, goes deeper than the 12.5 inch while still being manageable and transportable.
10 years ago, we saw our way clear to purchasing 4 acres with a small home and a garage in the high desert, a getaway and a place to observe. After a year or so, I realized that this was really a perfect location for a large aperture scope. A garage big enough to store it assembled, skies reasonably dark and clear. So, I decided I'd keep my eye open and see what came along. The 16 inch was plenty but this was an opportunity where a larger scope could be used without much hassle.
At some point, a 25 inch F/5 Obsession became available at a good price, it was within driving distance. My wife and talked it over and we decided to buy it. I had it for about 7 years, an amazing scope. But as I was approaching 70, I decided it was just too much. The eyepiece was 10 feet off the ground, I observe alone, if I were to fall, that could be it for Jon.
So, I decided it was time to down size. I found a 22 inch F/4.4 and bought it, sold the 25 inch F/5 and here I am today, the 22 inch is still a very potent scope but it is smaller and just the right size. Big enough but not too big.
I think David is in a similar situation though probably the skies are not quite as dark. Some sort of a larger aperture scope that remained assembled and could be rolled out and ready in 5 or 10 minutes could be a good fit for him.
I don't always use the 22 inch, the 16 inch gets a lot of use just because it is an easier scope, I definitely see more in the 22 inch so those nights when I am hunting down faint galaxy clusters, the 22 inch pays it's way. But there's plenty to see in a 16 inch and someday, if all goes well and I age gracefully rather than catastrophically, it'll be my number 1 scope, again..