As I said earlier in the thread, I do believe that there is some economic benefit to having the monarchy, though I agree it's hard to be exact about it. As the ones advocating change, I see the burden of proof being on the republicans. Research is needed into tourists' decisions to visit the UK rather than other countries.
However, I do see another, admittedly minor benefit. The longer I live, the more I buy in to the idea that they contribute to social cohesion.
I didn't attend any parties for the jubilee; I haven't been down to London to stand in any queues; I've never attended any event attended by a royal, and I wouldn't go out of my way to do so.
However, I am struck by the sense of community, identity and belonging that those events foster in those who attend them. Republicans might argue it's irrational, and that people shouldn't feel like that; however, the hard truth is that people do feel the monarchy brings them together, and who are republicans to tell them how they should feel? I don't think republicanism can bring people together in that way.