Thickness of the Gates Blue T104RB excluding tooth height is averaging 2.35 - 2.40mm measuread at various points around the belt and on both sides. I will be able to measure a Gates HSN and JHPS belt tomorrow.Did you ever measure the Gates HSN & JPS belts? I just measured a new Flennor 24513311 black belt, and two other used belts I couldn't identify, and the readings were all 0.088-0.089 inch (2.235-2.261 mm). That's about 0.004" / 0.1mm difference between the blue & black belts. Not as much as between the blue & black HTD belts.
Stretching my memory, but for the HTD belts, I think the difference was more like 0.016-0.015"), and that made about a 3-5 lb difference in Burroughs readings.
JHPS Belt Gates T104 White writing - 2.40mm - 2.45mm
Gates Green T104 HTN Belt - 2.50mm +0.00 -0.00
Gates Green T104 HTN Belt - 2.40mm - 2.45mm
Gates T104RB Blue Belt 2.20 - 2.30mm (I ordered two belts this is the second one, the first is measured above with different verniers).
The above all measured with the same verniers in the same way, so could account for the discrepancy. The blue belt was +- 0.05 around the belt with tolerance whereas the black belts were pretty uniform. Interestingly the two green HTN Belts measured differently with ~0.1mm difference.