What is the weight of this build? Is eTap compatible with 1x? This would be close to my exact spec - love the clean look of it.

Yep, you'll be almost going 50 mph at that point.

It isn't just the gaps between gears that are a large difference in 1x versus 2x on road/gravel apps. It is also the fact that with 1x you are not only riding with your chain at a much more extreme angle when near the biggest and smallest cogs in the back, but the very fact it is 1x also virtually assures that you will spend a good deal higher % of your riding time in those extreme angle gears near the extreme boundaries of your cassette versus a proper 2x set up where you can spend much more time riding near the center of the cassette as it is meant to be done. There is simply no way to get around those gearing facts. With 1x you are also assured of wearing out chains, the rear cassette, and the single front ring faster than a 2x set up maintained to the same degree of competence. On top of that, almost all sane 1x riders will be forced to use some type of chain catcher in place of the lost front derailleur up front. When you factor in that weight plus the huge MTB type cassette you end up running in the back, and a usually longer chain to wrap that huge MTB cassette the hyped weight savings of a 1x system is almost nonexistent vs. a comparable range 2x set up. Well under 100 grams net if comparing similar grouppo components in almost all instances. You basically lose a front derailleur, gain much larger gaps in your gearing, assure that you will spend much more time riding with your chain at an extreme angle versus 2x, save little to no meaningful weight, and wear your components out faster in large part due to those continuous extreme chain angles and running only 1 ring up front. Sorry, I can see 1x making complete sense for cross racing and even some MTB applications, but for road and gravel type riding it seems like a complete fad/gimmick that provides far more negatives than positives. And the "complexity" argument is nonsensical given how good current 2x systems like di2 have gotten where you essentially set them and forget them.

Far more extreme chain angles required to be ridden far more often with 1x on the road, much faster wearing out of components with 1x due to thise extreme chain angles, much larger jumps between gears, and almost no serious weight savings. And the complexity argument goes right out the door with a 2x set up like di2 where you set them and forget them. Other than that 1x on a road/gravel bik sounds marvelous. You can have 1x all day long. I'll "suffer" with my much tighter 2x gearing, far better chain angle (think more efficient), much better wear of components, and very minimal weight penalty. LOL