I own a Knight Wolverine II which uses the #11 caps and has the 22 inch barrel. I also own a Thompson Center Black Diamond XR. This rifle has the 209 ignition. Both of them are great shooters.
First the issue of the open breech. It really is not all that big of a deal unless you intending on hunting in the shower. I hunted in a snow storm and the rifle still fired fine. Granted, don't dare the breech to get wet, cover it with some handi wrap when your walking and hold your hand over the breech when your sitting. They also sell breech covers which fit over the open breech if it really worrys you that much. Put a finger cot on the end of the barrel and your waterproof.
The idea of the 22" barrel should not bother you. My Black Diamond XR has a 26 inch barrel but it is really not more accurate then the Wolverine. If you were shooting 150+ yards, then the longer barrel might be a plus. If your shooting 100 yards and under, don't let the 22" barrel scare you at all. All the shorter barrel does is limit the amount of powder you can really shoot. Although they are magnum rifles, with a 22" barrel you would not want to shoot more them 120 grain because there would be unburnt powder flying out the barrel. Also most of your accurate loads will come out at about 100 grains of powder... so the shorter barrel is not a problem. Especially if your going to scope the rifle.
My Wolverine II if you load 80 grains of Goex 3f or Triple Se7en and a 240 grain T/C Mag Express XTP the accuracy is excellent. Even harder to believe accuracy when you shoot the expensive 250 grain Barnes Expanders. It also shoots Powerbelts and other projectiles excellent. I put a Bushnell Trophy RED DOT on this rifle and it is an excellent brush rifle. I use it in my tree stands. The wolverine is a great rifle. A real workhorse meat and potatoes rifle. It is also easier to clean then the Black Diamond XR.
The Black Diamond XR is an excellent shooter. It will shoot almost anything you want to shove down it for some reason. I like to shoot 460 grain Conicals out of it. I also have some other pet loads for the rifle. This rifle I have a scope on and use during the modern season. I would not worry about a 150 yard shot if I had a solid rest and the animal was not running. A broadside shot, I would knock that deer down I really believe this.
Both the Knight and T/C have excellent customer service and warranty. If there is a problem they fix it. I have used Thompson Center's customer service and warranty, and there is no questions with them. You have a problem, they have a solution. CVA has a good warrany I was told but never had to use it. I also have a CVA Staghorn and it is a good shooter. But there is that barrel issue out there.
I really would hate to pick one rifle over the other. If I were going to do a lot of walking, I would take the Knight. If I were stand hunting, I would use the Black Diamond. Tonight I took the CVA. Tomorrow night, who knows....
When you shouldered the rifles, which felt better when you pulled it? The Knight or the Thompson center? You might want to consider this when you choose. Recoil is not bad with either rifle....