Coming from the chain side of the house...chains while having come a long way with O-Ring sealed link pivots and such still have issues with cleanliness and wear. Since it's introduction in the 80's, the belt made by Gates has evolved into a clean, durable and efficient system.
Belt drive is the way to go. The dig early on was the strength of the teeth verses torque and horsepower that has been addressed, using aramid/kevlar fibers and such. Going from one type of drive to another is expensive, personally I would leave as is, if you are like the machine...otherwise pass, if this is a make/break decision.