Had Black Diamonds and Knights. Definitely preferred the Black Diamonds. The Black Diamond was much easier to maintain as the striker is much easier to clean than the Knight.
To do a proper job on the Knight srriker, you must take off the screw on the end of the striker ( usually lock tited by the factory), remove the secondary safety and then you can take off the end cap to clean the spring and striker body. Assemble in reverse order.
The Black Diamonds are much simpler. Unscrew the end cap, remove the spring and handle retainer, pull the striker back, remove the charging handle and the bolt. I've had 2 Black Diamonds, and my Firehawk ( basically the same arrangement), never an issue with any of them. Never lost a part. I consider the Firehawk to be, my, perfect muzzleloader. Great handling, ACCURATE, durable, utterly reliable and easily maintained.
The Knight is a fine rifle too. Just takes a little extra work.