I tried a set of Martin ball-end nylons on one of my steel-string guitars and was totally unimpressed. The wound strings sounded okay, but the nylon unwound strings sounded dull and had no volume. I guess steel-string bracing patterns make the top too stiff to respond to the nylon strings.

Extra-hard tension strings might help. You can't get them in ball-end, but you can just tie a knot in the end.

I use silk-and-steel strings on my 0015 Martin. They're a nice compromise between regular and nylon strings. Have you tried them? I think they're almost as comfortable to play as nylon.

Bruce