From the latest Ask The Devs (#27):
Garth Erlam, on 03 December 2012 - 04:27 PM, said:
Q: Can we please at least try DHS at 2.0? It doesn't seem like much of a boost to lights who usually benefit mostly from the engine heat sinks, but heavies and assaults that use big energy weapons need the boost. [Wolfways]
A: No. Prior to releasing the Dual Heatsink upgrade the forums were abuzz with whether or not they would be mandatory on all Mechs. With the numbers we've chosen, they aren't, so I'd say we answered those questions well. [Garth]
Now I'm not sure if most people in favor of having all DHS at 2.0 feel the same way, but I don't think the goal here is to make SHS even less relevant than they already are. My primary concern is the effect the current DHS values have on the viability of high-heat weapons like the ER PPC. Heat should definitely be a big factor with these weapons, but not annoyingly so. At least not when you've equipped a reasonable number of heatsinks.
I actually really
like the idea of SHS still being viable for certain mechs, if only to promote build diversity, so I share PGI's concern of the performance delta between SHS and DHS being too large. I do however think there are more elegant ways to address the problem.
As multiple people have already pointed out, with engine internal DHS at 2.0, DHS mechs with a 250+ engine essentially already get 10 SHS for free. They straight-out save the 10 tons and 10 criticals that SHS mechs would need to have equivalent dissipation. This is probably the main reason many players never even
consider choosing SHS over DHS!
At the same time mechs with high heat weapons, which have even less reason to consider SHS because they tend to have the space and need all the heat dissipation they can get, get shafted because external DHS are set to 1.4. No wonder these weapons don't see much use at the moment.
The only way I see the current values making sense is if PGI wants SHS to
only be viable for these high heat builds, which seems odd to me. They'd be more interesting if they were viable regardless of the amount of heat dissipation needed.
So, hence my previous suggestion of at least equalizing DHS values and setting them to something like 1.8 or 1.75, which has the added benefit of being easier to understand.
This doesn't really change the overall performance delta between SHS and DHS. That could however still be achieved by making the Coolrun efficiency, which is easy to unlock, substantially more effective when used in combination with SHS. I'm not sure if Coolrun also affects total heat capacity but it could of course be made to do so.
Finally, if we consider that a DHS with a value of about 1.8 would have an effective efficiency of about 2.0 when taking into account the (maximum) Coolrun bonus of 15%, it would not be much of a stretch to nerf the Coolrun bonus for DHS to a single digit percentage or remove it entirely and simply give DHS a native value of 2.0. This should also satisfy the purists among us, though some might say leaving it as it is (and still having an effective efficiency of ~2.0) is already good enough.
While you might object to DHS getting all the performance up front, consider that Coolrun (750 XP) is usually unlocked before the DHS upgrade (1.5M C-bills). There is of course the factor of having to unlock all Basic efficiencies on 3 variants to get the full bonus, but this too could be tweaked to not be as big of a deal.