I carry a TC Barlow in saw cut red bone every. single. day. I broke the pen off several years ago doing something dumb. (The post is here if anyone cares to search for it.) I was going to send it in to be replaced, but honestly I kind of don't mind it. It's just part of the history of the knife, you know? Once in a while I'll pull it out and wonder what it would be like with that single spring, but I've never done held one so I don't know.
I have a two blade boys knife in clip that I'm not crazy about the bone on. If it had a long pull I'd send it to Glenn or someone in a heart beat to be made into a single blade with ebony, but I'm not sure how I feel about the nail nick over the long pull.