i've really been eyeballing the specialized allez to replace my old road bike, but the geometry appears to be more relaxed this year, so I'm trying to decide if the 54cm would be right for me, versus the 56. The reach of the 54 is 380mm, similar to my 56cm cross bike (which I really like) and 570mm stack (583 on the CX, although it has some spacers).
The 56cm version of the allez has a reach of 385mm and stack of 596mm and apparently 175mm cranks (I use 170 on my road bike). My current road bike has a stack of 55cm and a reach of (I believe) 385mm and I have a +17 120 stem on and saddle height of around 75cm from BB.
Anyway, I realize it's a lot of numbers, part of the problem at the moment is that no local shop has both sizes for back to back comparison, so trying to do my homework beforehand, I'm leaning a little toward the 54 as it seems to be a good balance between racing and endurance whereas the 56 seems straight up endurance geo.