Just a heads up for those buying components ahead of getting the frame: the chainstays are 30mm at the flatmount bolt holes (so you need Y8N208030, 43mm).
Frame looks great -- love the rainbow paint job. Weight within spec. It built up really easily. To keep things simple, I'm using a regular stem and handlebar, and I'm running full-length cable housing to the rear derailleur, so I had to slightly drill out the provided plug (which would normally act as a cable stop), and I "repurposed" the included di2 plug for the hole where the RD cable housing exits the frame.
Now waiting for the bolts and a new headset (affordable IS52/28.6 | IS52/40 choices are a bit limited) to complete my build (long story, I broke one of the bearings of the included headset -- the fit was super tight and I accidentally opened it while trying to removed it).