Someone commented on that issue, and this was the reply:

JarnoBierman wrote:

23 vs 25 should be good for .2 - .3 watts @ 120 psi and ~ .5 - .7 watts @ 60 psi. I'll dive into the differences in the casing and coatings later when I have time to finish the text.

So according to him it narrows the gap, but is not "identical."

He really needs to compare apples to apples by doing a test on the original CS TLR in 25mm width.

I totally agree. Anything else is speculation. Also I just have to wonder what technology he uses that can accurately measure 0.2 watts difference out of 7 watts? And that's not even counting the fact that you can get that much difference with even a few degrees of temperature difference in the tire, or from different samples of the same tire, or even remounting the tire differently. I feel like he needs to put more weight on the tire so the rolling resistance is more like 50 watts (what I do) and the differences are more apparent.

I agree. I can understand switching to 25 as the new standard for testing given it's probably the most common width these days, but given this is about the very fastest tire (in Crr) a direct comparison should be made.