Well, it took a while to get the build finalized because the lackluster shop I worked with did the single worst job assembling a bike I've ever seen (and they forgot to send a bunch of parts).
In the final spec, I changed out the Power saddle for a Fizik Antares Evo 00 Adaptive. There's something about the shape of the Power that is really painful for me.
It's great to be back on Di2 after a couple of years with SRAM Red AXS only. The shifting is definitely crisper and more predictable. I do love the 33-33 combo on AXS however as well as the ability to stay in the larger chainring more often . . . it'll be interesting to see what Shimano comes out with.
I have a couple hundred miles on the Aethos. The ride quality is incredible. At size 52, this bike is less long and low than my F12 which means it's a more casual and comfortable ride. I have ridden on the Turbo Cottons before, and I have to say I really love them. Although I've gone mostly tubeless, I don't mind going back to tubes for the ride quality you get from the TCs. The TCs with the Roval Alpinist CLX actually do a better job of absorbing road chatter than my Zipp 353s with 28 mm tires.
The Aethos reminds me A LOT of the Canyon Ultimate EVO I owned for a while, but it improves in the one area where I thought the Canyon was lacking - stiffness. The Canyon felt a bit noodly when out of the saddle and you'd get all kids of brake rub when sprinting. The Aethos fixes this one key issue. Like the Canyon, the Aethos surges forward with pedal strokes, probably a result of the super light wheels. It feels great on climbs, but it's mostly just a feeling. As I discovered last summer, I can beat my PRs with my heavier Pinarello without noticing any significant difference. But the feel is certainly different.
The Aethos is a confident descender, but I've noticed a tiny bit of understeer. It's hard to match the descending confidence of my F12, which is like riding a railroad. All-in-all, it'll be a great all-around bike. Fun for long rides and the time I spend in the hills (which is most of the time). I really love Specialized's new paint jobs. I have something similar in green on my Epic. The color really does cool stuff in the sunlight.
The final weight with two Arundel cages and Speedplay pedals is 14.25 lbs.