The heat is dumb in principle and sucks. /thread.
Okay but seriously, I don't get this. I'll start with jumpjets - why do we need the massivehuge wtf heat spike? Now Toth already mentioned that they'll lose some heat generation in future versions (or at least he suggested it might), but I'm more concerned with any high level of heat generation period. And here's my case on this one:
Jumpjets are tricky to use. By and large most of their use is constrained to utility (terrain mantling and environment navigation) and poptarting. Another common use is dodging long-range artillery fire (LRMs, Arrow IVs, Fbombs). The role of JJs in combat is ridiculously situational and in many cases questionable, as it more often than not can spell your doom. Associated with the use of jumpjets is the massive list of caveats. Short burn time. Extremely long recharge. Limited mobility. Predictable movements. Complete loss of speed on landing. Screen shake. And, the tremendous heat buildup. The heat generation is so intense a single full burn generates heat on par with a PPC alpha strike or Heavy Large Lasers. In other words, if you use heat to take the edge off the most powerful weapons in the game, jumpjets are godlike weapons of mass destruction. I find that claim debatable but that's not the point.
The point is, jumpjets severely and unfairly penalize their use in combat for really no good reason. Poptarts, long-range dodging, and terrain mantling have very little need to worry about the heat all too much, as in all these cases it's unlikely you'll be firing all your weapons full-bore, running at high speeds, and being extremely reliant on all your mobility and the full capabilities of your mech for survival. The very nature of poptarting lets you just cool down, idly fire your jets, shoot your weapons, maybe tap some coolant, land, and casually wait for it to recharge. Using JJs in combat to perform tricky maneuvers like evasion and escape is punished by the caveats more than any other use. The speed drain is utterly lethal, the heat generation *will* push your mech so far into redline you could lean against a rock and melt a hole in it, the general predictability and rather slow speed means you often times end up as an easy target, and the short burn time / long recharge means if and when you use them, you'd better use them right because you might not get a second chance.
So my point is this: Are jumpjets so lolimba that we seriously need to have anything more than a very modest heat penalty applied to it? Something on the order of firing an MPL or two? The heat penalty only serves to punish the hardest way to use them, and I just don't see the damn point. Aren't they crippled enough in other ways? Even without the heat they're still going to be painfully difficult to use well. It likely wouldn't even lead to additional jumpjet use, as the existing list of drawbacks impressively already curtails their overuse (that and the overlong recharge time).
The draconian penalties and permanent damage associated with excess heat generation in 0.4.X precludes the use of these things even nearly as effectively as they used to be able to.
On a secondary note, I personally believe that MASC should be able to be used much more freely than it can be now. Adjust MASC heat generation to follow a curve - lots at the beginning, less at the end, so that if you're doing nothing but moving, you can MASC without limit. MASC while already hot will push you over redline just the same as it is now... but the difference is you don't need your mech submerged into the bottom of the Arctic Ocean to use MASC more than a few seconds without setting fire to trees you pass by. Effectively this means that when you have MASC on, you lose a huge chunk of heat capacity. Your choice is mostly to use mobility, use weaponry, or be skilled enough to balance both. Mostly I want this change due to the new heat penalties making a hot mech much less viable to play as and the minor benefits this would provide to MASC-capable mechs as far as raw mobility is concerned.