True but with some frames specially these ones since the seat post is proprietary u have to realize that no matter how short his upper body is, the seatpost has a limit too so just stick a broom in the seat tube is not an option even tho it is a common practice too.

The op is so tall that the seatpost in the 55 will be too short for him, in a matter of fact probably at the limit in the 57 too? the op IMO actually is kind'a between sizes and that sucks hehe Because makes you doubt. For the record is easier to figure it out if the frame is tad small than tad big.