A fantastic read - thanks.
Quite simply I'd hire someone to do the dirty work, pay them a decent salary and split the remainder of the income between you and your co-founder.
Sounds like a pragmatic solution. The product exists, people keep signing up, and maintenance is minimal. I can completely understand why the Pennarun dropped out, though, since I would loathe working in a career where my job was to fill deficiencies in a product I don't like. It sounds like the real problem is the web of hacks. Nobody likes hacky fixes--they can wear a person out.
I think his article may have been a desperate plea for such people to come out of the woodwork. I implore you to contact the author and refer those people.
I've actually had the pleasure of meeting both of them in real life and they're great people -- honest, smart, fun to talk to -- I imagine they would be great to work with.