#12-6", Sportsman's Bowie does not come with thumb notches. They are available, but uses one of your 5 options.
A #12-8" has much more artistry and "sweep" than a #12-6", Little Bear. The #12-6", "LB" also has a more traditional finger choil than the "Big Bear". Once you get use to them, they are easy to differentiate.
In my opinion, and this goes against everyone elses', I think the FCH is too heavy. I like a nice #1 styled double hilt. About an ounce difference, whether it's 'proportioned" or not...It's still a good bit heavier...and every now and then the Randall craftsmen don't get the FCH's quite small enough.
Best, Capt. Chris
P.S. They do look good though! (The FCH)...CCS