While the benefit change from Discoverist to Explorist is relatively small, if there is no cost to moving a few Marriott nights to Hyatt, why not do it, assuming that the locations and quality of the the Marriotts and Hyatts on those stays are comparable? Don't move a JW stay to a Hyatt House 15 miles away, but given comparable hotels for those nights, the move to Explorist might get you an upgrade that you couldn't normally get at a low occupancy Hyatt in the future, where it most certainly won't get you anything with four additional Marriott nights.