Fantastic, fast, fun!
I've been super happy with my Solo C90. I was reticent to go with a 1x set up as my previous gravel bike, a Lynskey GR260, was set up with a 2x Di2 set up. SRAM have nailed the 1x, though, and it never skips a beat. The stock wheels are surprisingly nice and ride well, though I do swap out to some lighter wheels for bigger rides.
The frame and fork are really well thought out and ride great. I had a Redshift stem and seatpost on my Lynskey and thought I might miss them, but the Solo is surprisingly supple and comfortable.
My one complaint about the bike is that it didn't come with covers for the down tube cable routing that completely close of the frame to prevent water ingress. I'm sure I'll come up with some sort of solution, but given all of the different covers that came with the bike, a solid cover seems an obvious choice.
Thanks for designing a great bike that has rekindled my love of gravel riding!