The testers who posted about this made clear that their dependent variable was the heat efficiency statistic in the mech lab, NOT the performance of heat sinks in-game. When their results were misinterpreted by many, they kindly tested heat sinks in-game and concluded that the diminishing returns applied ONLY to the heat efficiency statistic. These tests were done with singles.
And, yes, DHS are currently bugged, and the devs are working on a solution. they said this should be out no later than the 6th.
Edit: Yes, what they said ^^^^^.
Edited by BD Magnum, 30 October 2012 - 12:08 PM.