Very much my kind of fiddling!
I'm very open still with retro narrow cut-down flat bars (520mm - 530mm) and bar ends. Like you say, so much depends on your local circumstance and so there can never be a right or wrong.
The thinking I have at the moment is to pursue 26" - I note that I'm physically smaller than you looking at your bikes. I've ridden 29" MTB and I didn't get along with them. Felt sluggish where I expected a tight MTB frame to excel in being nimble.
Stuff related to tyre contact patch size and capability I'm very much in the 26" camp. Where it all trips up not so suitable for very long distance with mixed terrain; I'm also not adverse to a good well built Hybrid either. Personally find these bikes are great for discovering.
Drop bars in the equation really makes something much much more suited for longer distance planned rides I find. It's also nice to push them a bit just to see how far and capable they are off road.
It all sort of boils down to time in the saddle for a given a distance and given terrains. It is very personal when we add the fact our tempo can change over mixed terrain depending on interest and what is around us. Some descents are worth belting down tooth and nail, some are worth taking the time to enjoy every minute after struggling to get there.
In general, I've found these types of builds with skinnier 700c tyres extremely capable and knowing the limits really helps when to put the anchors on and avoid mishaps and put the clog down to keep a smooth pace going. Find it always astonishing what the pro level CX guys can do - full on gas and incredible bike handling skills.
I just wished the bike industry actually did something years and years ago rather than it doing a self colon exploration mission. I find it almost insulting on their part if you are tempted to this on-road / off-road mix - apparently you needed to wait for a specific gruppo. It is absurd to think specific gruppos were needed to be invented and marketing to "fill" this task along with a new "Gravel" movement on what is pretty much a big boy sized retro 26" MTB.
All we wanted was consistent interchangeability of parts from about the late 90s and onwards.
