I have had two langsters, and liked them both, but never loved them. A surly steamroller however is a really lovely bike. On paper it does not match up (steel Vs crabon forks), but the ride and emmotional connection is far greater.
Sounds like intangible hippy twoddle, but I know several other people who have gone from langster to steamroller and they have said much the same thing.
The complete surly comes with a great frameset, and great hubs, which is the most important parts on a fixed. I have seen some shocking downgrading on other fixies as they struggle to hit a price point ( £2 dicta freewheel on a £550 kona for example)
Hope this helps…