I think I already mentioned that I as a guitar player also once tried a six string banjo. It wasn't manufactured well, very difficult and hard to play. But it still was some great new experience: Because of its completely different sound pickings that sounded good on the guitar didn't work at all on that banjo, and vice versa. I didn't know before that there are things you can do with one instrument but you can't with a different one just because of the different sound and no other reason. And - when accompanied by a guitar - the result was kind of better than what I could have done with only a guitar played by myself.
So I don't object too much to experiments like banjo mandolins etc. Think of the saxophone: also some kind of bastardaharp, a clarinet mouthpiece fitted to a brass instrument. But what success!