The cloaking device seems bugged, in my game it's not limited by the size of the ship in the same way a jump drive is. For example I cannot complete (lock) a design where the hull size exceeds the jump drive rating. But I can complete a design with a 1HS cloaking device and 90% sensor reduction with ANY hull size, including the superdreadnought of 1. 5m tons. Furthermore it actually reduces the cross section of the ship both on the design screen and versus enemy sensors. If intended why does the cloaking device efficency matter?