I'm in the process of buying a new bike. For me this process is awful. I am 6' 3" with a long inseam so typically the size bike I need according to sizing charts is a 62 / 63 (when using numbers) and a XL (when using letters). The difficulty I have is that no LBS stocks a bike this large ever, NONE, NADA that's it. So for me I am essentially buying sight unseen / sat on / test driven all not possible.

I have to look at geometry charts comparing new bikes I"m interested in to my current bike which from a geometry and size perspective has me in the right position (back a little lower than 45 degrees toward the handle bar). My current bike (Kestrel RT 1000) has a Stack to reach ratio of 1.57 and I put a 17 degree 110mm stem on it. The stem effectively increases the S/R however it's hard to say how much. Anyway this setup is just fine for me and I have built a chart of bikes based on head tube length and angle, top tube length etc. along with S/R.

How much can I rely on the S/R when finding a bike? The Trek Domane in my size has a S/R of 1.7 while a Canyon Endurace has a S/R of 1.54. Oddly enough the racy Trek Emonda has a S/R of 1.59 and the Bianchi Infinito is a 1.58. One would think that a correct position (not too low / aggressive) would be had on any bike that has a S/R greater than 1.57 (my current bike). Is this the S/R figure worth looking at or does one need to look at all the measurements in concert? The bikes I have charted are as follows, with corresponding Stack To Reach Ratio in my size:
Canyon Endurace: 1.54
Ridley Fenix: 1.55
Giant Defy: 1.57
Bianchi Infinito: 1.58
Emonda; 1.59
Domane 1.7