Bruce, I understand your passion for the gills more and more as time passes.
An interesting observation that may or may not hold true, when our CNBG hit about 9 inches they seem to become much broader and thicker.
Maximum length presently seems to top-out at about 10.5 - 11 inches, and increasing weight gains to 1.25 – 1.5 #’s.

Thanks to Todd and Eric for educating me on CNBG ID, I am now more comfortable on culling.
I find if I hold them in a live well until their colors have stabilized they are easier to identify.
The younger and smaller are the ones I have problems with.
If they are iffy, they go back home.