It's easier 'use' the 'cm-scale', IMHO. Seems more consistent. (Don't ask me why, but...) I currently play wearing: (1) Yonex SHB 99 (2) Asics Gel Rocket (3) Adidas Court Stabil (4) New Balance 752 I've worn (to the ground): (1) Mizuno Wave Blocker 3 (2) Pro Ace (can't remember model) (3) Hi-tec Viper 400 (4) Fleet (can't remember model ALL were size 28.0 (cm), and yeah, they fit(ted) me well/correctly...
i agree with punchclear. i got my dad in china to buy me a pair and I gave him a size based on the CM length of my foot. it worked.