For a one person operation, especially a switching layout, with walk around capability, I'd recommend staying with the DC system you currently have. Unless your walk around is causing problems, you don't even have to go to wireless DC.
The benefit of DCC, for your situation, would be; constant lighting, sound, and walkaround for little extra expense (front panel plugs, and cabling). Digitrax throtles (most) come with infrared. All that is required is the infrared receiver (or two, infrared is line of sight)) for wireless walkaround.
The QSI equipped locos run on DC, but aren't exactly DC friendly. For one, you have to open about one third throttle before they respond.
Pete