Considering the small amount of time you spend riding, why are you considering upgrading? If what you have is functional, find out how large a tire you can fit on it and the ride will definitely improve. Disk brakes are good, but they also make some really grippy caliper pads today that will impress you. Clean it up, lube it up, throw on some larger tires and better brake pads and enjoy. Spend that cha-ching in your pocket on .......