Damn my 97s are basically silent on skatepark concrete, kinda miss my board having sounds. I swear the 93 were louder.
Skated a little today trading boards around, between us there was new 97, old 97 and the 93s. The new 97 was definitely loudest, chirped the most on slides. It also rolled the fastest on metal by far.
The 93s were faster on the rougher concrete in the flats than the new 97 by a slim margin. Both had swiss 6 bearings.
FWIW on size/shape:
57 radial, new 97. Full diameter
54 classic, old 97. Barely worn, maybe 53.5
54 radial, 93. Worn to about 53 to 52.5ish