I know OpenComputers was removed because it was dangerous. With ComputerCraft, you can limit threads used, and RAM used by the mod, you can also limit the websites accessible by the http api, the number of open requests, etc.
CC Turtles are also supposed to obey block protections, but if they don't I think it'd be okay to outright ban turtles (or just remove the movement api from them via config, as it's other apis have the same level of claim bypass risk as thermal itemducts).
Also, I'm pretty sure that those same things could apply to OpenComputers, and personally I do believe it's a better gameplay than CC.
Also, I'd recommend CC: Tweaked over ComputerCraft. It's a drop in replacement, with some extras, including a built in profiler for server admins, and is much more stable.