I wouldn't choose to sell him. He's very good, but not great. He doesn't score enough goals and his passing can be terrible at times, so for £60m you'd almost certainly be able to get a better replacement.
I'd bit your hand off for 60 mill. I like SJM but I think if we got a id like that I'd be cashing in, I often think his work rate and his song often blinds some fans to his actual return performance-wise.