CB Range discussion

I have a query for CB6000S users. I’m about to purchase either the standard CB6000 or the CB6000S, and since my flaccid measurement is exactly 2.5 inches, the S model looks like the correct fit. However, how important is thickness?

I’m not entirely sure what size 1-3/8” really translates to in practice, but even though I am short when soft, I do have a bit of extra width… Another worry is that I tested a metal lock with a 2-inch ring and couldn’t manage to get my testicles through it for the world. So, I’m hoping the 2-inch ring size will be sufficient.

Any tips before I spend $150 on one? Cheers, Sprockett