It's rare to see a stem that fits a bike so well. It has the same angle as the top tube and the carbon matches the seat post/head tube.
The rest is built up beautifully, too. You didn't just threw the most expensive parts on there but parts that acutally fit. The only very minor change that i could think of are AX Lightness wheel with a 3k finish.
That stem was exactly for the purpose of matching the carbon on the other tubes. Its a nice looking piece of kit but it just fit the build. I also initially wanted a little more traditional TT which Rob was happy to do. But he suggested more slope, this would build a smaller lighter triangle, have more seatmast showing=more compliance, and so the stem angle would closely match the TT angle for aesthetics. He is the builder so i just agreed to whatever he suggested. He also always builds with a 10mm spacer under the stem, in case you swap headsets later on down the road or stems with a different stack height. He will slam it if you request it but I liked his reasoning not to.
I looked at all sorts of wheels. Schmolke SL 45 tubs were my second pick but I have had such good luck with Bont Aeolus wheels. Plus I get a heck of a deal on Bont/Trek at the LBS I work at from time to time.
The crankset was the only component I really went back and forth on. Originally went with a SRAM red BB386 crank with a BB to make it work with BSA but it was on the porky side and just not crazy about the look of it on steel bikes. The lighning crank did it all, removable spider, 30mm spindle that works with the BSA BB shell, made in the USA, black decals. I like the look of the narrower crankarms with steel tubes.