Ted
I just mentioned the Whisper cartridges because they seemed to fit your requirements for shooting heavy for caliber bullets, small case, subsonic silence ability. When you stated those requirements the Whisper cartridges immediately came to mind.
I like the little cartridges too and have some experience with all the ones you mentioned. I had a Marlin 25/20 that I was very fond of. On what I knew would be my last visit with my adopted Dad he expressed a desire to have the rifle so it went home with him and it brought me pleasure to leave it with him.
Now I am expecting delivery of another to replace it any day. I do like the cartridge especially in the little lever gun. If I were to have any other action type and wanted a small case 25 cal and since I also have some very positive experience with the cartridge I would be looking at the 25 Copperhead. Since the longer 222 mag brass is now readily available in the form of the 204 Ruger I would also be looking closely at the 257 Kimber.