Y axis is heat efficiency, X axis is number of external heatsinks.
100 engine

245 engine

300 engine

As you can see compared to the current DHS, the new ones are in some cases better.
For the other cases it's slightly better. For the 245 engines the intersection is at 6 DHS, meaning that if you have more than 6 DHS you will have worse efficiency than now.
For the 300 engines that point is at 8 DHS.
In conclusion,
EDIT: Correction after studying the graphs some more I have come to the conclusion that this will benefit no one and will in best cases keep thing the same and in very rare ones will it actually increase HE.
Edited by NamesAreStupid, 02 November 2012 - 02:59 PM.