RE: T/C Black Diamond vs. Omega thumbhole
The Black Diamond is a great rifle, but it has a few problems. The open bolt design allows twigs and pine needles to fall into the ejection port if you carry the gun cocked, with the safety on, and a primer on the nipple. If this happens, the rifle will likely mis-fire. Notto mention the possiblity of the cap falling off the nipple with nothing much to hold it in there.
If you carry it "hot" with the bolt in the forward position, there is a possibility of bumping the little handle on the bolt - which could cause an accidental discharge. The only safe way to carry this rifle in the field, IMO, is to not put a cap on it until you are ready to shoot.
I have had two accidental discharges with mine. Neither were the result of carelesness. But, nonetheless, I still hunt with it. We mainly hunt from "stands" and this allows me to not cap the nipple until in position at the stand. But walking through the woods with this gun with a cap on the nipple scares me . . . .
Get the Omega.