I just measured both an 18 and a 23 toth new Shimano sprockets as 2.16 to 2.25mm thick and a 24 tooth Sachs cog as 2.10 to 2.12mm thick. The Sachs cog does seem to be a bit thinner and more consistent in thickness. It looks to me like the SRAM cog has the teeth area more polished to remove stamping related burrs and high spots before final finishing. The Shimano cog is chrome plated while the Sachs one appears to be Parkerized like many military guns. The 19T SRAM cog that came with my P5 hub is 2.0mm thick nominally.
Good luck in finding the SRAM cogs in the USA. Mine, except for the P5 one, were bought from Sachs, pre SRAM buyout.
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Gear Hubs Owned: Rohloff disc brake, SRAM iM9 disc brake, SRAM P5 freewheel, Sachs Torpedo 3 speed freewheel, NuVinci CVT, Shimano Alfine SG S-501, Sturmey Archer S5-2 Alloy. Other: 83 Colnago Super Record, Univega Via De Oro
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