I don't understand the "it requires too much attention". Isn't that what managers are for ? Assuming your opportunities are profitable enough , just hire enough managers and be done with it?
Generally retail requires lots of efforts ( management must take care of really very little details ) and produces a very limited capital gains. You have a steady CF but you are always on the edge if you need to expand or innovate.
Who manages the managers and how do you trust them? How do you measure their value when it's possible to cook the books? A portfolio of managers seems less reliable to me than a portfolio of companies. At least in the latter case, you can all pretend that the other investors are doing the proper diligence.