You've likely already settled this, but the WT comes in 53 and 56, not 55. It's also measured differently than the TT and has a different geometry. WT is identical geometry to Steamroller. My guess is you'd be happier on the 56, but people also say it's easier to make a smaller frame fit to your needs. I can tell you that I'm 5'10" with 33" inseam and was told by a bike shop that the 53 Steamroller would be too small for me.