About 15 years ago I went to Brooklyn's largest high-end pro shop, R&A Cycles. Yea, those guys. I was looking for something high-end myself, but they really couldn't get me a ride on the bike that I liked because it was a custom build. Instead, knowing that I hadn't been on carbon before, they set up a nice Giant TCR for me to take a loop around Prospect Park, about a 4 mile ride. I was hooked on carbon, and bought the bike I still ride today without test riding. They almost lost the custom sale to that Giant, but I don't regret for a moment buying the Kuota with Chorus.
I should add that after taking delivery about a week later, they did a custom fit and had the thing completely dialed in. You can only hope that you are treated that way in a lot of shops. Also they upgraded any parts they didn't have in stock, not a huge amount but enough.