Duges is a good ball runner and possibly even better than hayne at kick returns (on average, slightly), but that's it.
More important than that IMO is safety, having someone at the back who you know will save the day if it's humanly possible. Contrary to his legend, Duges is merely human. Hayne is not. He's exactly the kind of superhuman you want at fb in origin.
There could easily be a gameplan for duges to support hayne on kick returns and even for hayne to pass to him so he can do hit ups on kick returns. To me that doesn't justify removing Hayne from the 1 spot.
I think it would be a lot to ask of Duges too. The scrutiny and pressure would be so immense blunders would be inevitable. Best to leave him on the wing. It's ideal to have 3 fbs as your back 3 anyway.