I'll never understand why bike companies continue to insist on giving us C-T seat tube measurements. You can tell more about the frame from the head tube length, which is the same at the sizes you're looking at, but pretty short at the larger sizes for the Tutto. Kinda hard to tell what they're going for. Also, if you want to get into steel nerd stuff, the main triangle of the Rush is Tange Prestige, which is arguably a nicer tubeset than the Tutto's Columbus Cromor.