Good list:
I just add the following that you covered because of the workarounds the Urbanite has.
• a more upright position
Only if you want it,you can drop as low as you want, and you have a longer wheel base for stretching out.
• a more stable frame (i.e. steers a little slower, a little bit heavier)
This probably speeds you up since you cut a nice steady line.
• stronger and heavier wheels
This is the worst news, but there lots of tweaks you can cutomize. Urbane cyclist will build you whatever wheels you think you need at no extra cost, and anything lighter than that may leave you with a broken wheel.
• wider tires with more tread
I just run slicks, but mine are wide. At a certain point when the road gets rough, I would be more hurt by the rough ride, hey, but I'm a geezer.
• gears is optimized towards carrying loads than traveling at warp speed
Again you can taylor that, it's only a problem if you get the wrong gears for your purpose.
The way the Urbanite is built out they will put whatever you want on it, they are pretty cheap when it comes to their bike packages, and they will incorporate components you want or leave them off for you to add. So in my case I had pedals, and brakes of my own. They switched out the saddle for a B17, and the brifters for brakes and barends, that was pretty much a wash. They built me rock solid wheels to my specs.