Hey Man, how many tapes do you have? I know it's a different thing, but i used to record over cassettes all the time on my old 4-track cassette recorder.. (well.. only recored over things that i didnt need to keep!) It woud get to the point where it would sound very mushy and hissy.. and let me tell you... i don't mind that of thing at all!! Music and process..
I’ve got a couple of reels. I’ve recorded over them several times now. I notice small things here and there, but nothing crazy to my ear. I’m going to get a new roll soon though.