Exactly my feeling about the difference. The OC-5 is more precise and the OC-2 is more idiosyncratic. Other than that, there might be some glitches making one sound a bit more growly sometimes and next time it's the other. The OC-5 is a true success : thanks Boss. No need to spend €/£ 200 on a second-hand Japanese OC-2 anymore, when you can almost get 2 brand new OC-5's for the same price.