I’m chiming in without reading many of the replies below: With my experience, which isn’t DK, TransIowa, Midsouth type epics, but with a CX bike as only bike for a while, as a commuter for a long time, and as the only mid-tire width style of bike I’ve ever ridden… 2x is imminently more versatile. Its not about the top end or the bottom end, or range at all: its about fine tuning your comfortable cadence while you’re on some rollers, into a head wind, or descending with a tailwind. When you’re wheel sucking faster guys, the difference between a natural cadence and grabbing up and down for gears can mean hanging on or falling off. (I still managed to fall off plenty of times, but wouldn’t want it to be worse.)
I won’t pile on specific manufacturers because people get offended, but it seems like companies, generically, are going 1x to hit an OEM price point, and selling it as an improvement. I weigh 189 lbs (85.79kg) on a fit day, why would I give two hoots about an extra 89g of an FD? I could leave my phone at home and save more than the whole difference between a 1x and 2x system.
I started with a 48/39 front (9spd-12-26? rear), and actually liked the spacing up front. It was small enough I could change the front more often than I would have been able to otherwise. That bike is now 46/36 x 11/28 (10spd) and I absolutely could have used a lower end, but that “problem” would easily be solved with a modern cassette (32, 34, 36 tooth). It did improve going from a 39 to a 36 front inner.
Now, my primary cx/commuter is 1x… but only because I moved from my previous rolling terrain to FlatLandia where I can ride 40 miles and have my Garmin register <200 ft of elevation gain. BUT, when the current left shifter fails, or the RD breaks, or, yeah, it will go 2x whenever there’s a part in that system to be replaced.
And I actually ran into this, after a crash in a CX race - my right shifter failed. I couldn’t downshift (go up the cassette to a lighter gear), but my left/front shifter still worked, so I managed to finish the race with a two speed. I think that variability was worth more on that day than the number of grams that could have been saved.
All things considered, go 2x if you’ve got the chance. Now, I’ll go read the rest of the responses.