Since you specifically say that you are not concerned about the money aspect. Your post sounds like you have an attachment to whatever title you currently have.
If you are truly interested in working on "real business problems" - then as a consultant, with a bit of networking, you will find plenty of them. Wouldn't that satisfy you? I seriously doubt that partners at consulting firms think of themselves as having been demoted. To the contrary, most are pretty pleased with themselves.
I suspect that you have grown fond of your impressive title at a recognisable big company. You are worried about what people will think of you if you have a less impressive (in your opinion) title at a less well known company. Dare I ask whether there is any social pressure from friends and family?