I'm building a new bike. I've always ridden 172.5mm cranks because that's what came on the bikes I bought. I purchased a Quarq from a teammate with 170mm arms. After considering replacing the arms with 172.5s, researching the web for calculators, searching forums including this one, etc., I came to this conclusion:

Nearly everyone is full of hoo-haw, I won't see a noticeable difference, and for the first time in a long time I'm not making another impulse based purchase.

Discuss.