You know, in general terms, one can go a long time in this game and never hear people bemoaning the fact that the AC/5 is too good compared to the Large Laser. Except when, for once in its miserable existence, it gets a single leg up, and then its the Devil...
Just kidding; really. But think about it: everything has stayed the same, except heat output and range[-bands]. Basic heavy ballistic weapons (half of them, anyways) have minimum ranges that have quadrupled, whereas most energy weapons do not. The damage on all weapons stays the same (though, arguably, Infernos got slightly more effective). The heat is quadrupled, which sucks, don't get me wrong. But so does the heat dissipation.
Every S7 turn is 1/4 of a BattleTech turn; the number of heatsinks stays the same and the work the same (i.e. -1 Heat per Single HS/Turn). So my lovely Rifleman fires an AC/5 (+8 Heat) and runs (+2 Heat) and at the end of the turn I shed 10 heat. So far, I've been running and gunning for 2.5 seconds. So, in true Dunkirk-style, by the time my BattleTech self catches up to me, I still get to do three more things.
Next turn (looking towards halfway through a BattleTech turn), I'm feeling froggy, so I'll unload a heavy laser and come to a bloody halt. At present, I'm at null on the heat scale. I jack myself up 32 points on the heat scale and immediately explode. Wait, now my heat scale goes up to 120. And I get to deduct 10 heat for my fabulous, Sphere-renowned cooling system. So I end the turn with +22 on the heat-scale.
Now into Turn 3 (3/4 of the way through a BattleTech turn), I'm a bit slower (-1 MP; just look at the standard heat scale and multiply everything by 4; that is literally all it is), but still happy I'm driving a Kallon original and not some Red Devil knockoff piece of trash. I figure, Hell, why not? and light off two medium lasers at my buddy leering at me from the other side of the arena as I backpedal. That adds +25 Heat (2 Medium Lasersx12+1 Walking). Now I am looking toasty with (22+25)-10 Heat, leaving me at +37 on the scale.
Now, on Turn 4, I'm slower -1 MP), and more dull-witted (+1 THM) than I was before. But because I got it like that, my opponent in his Archer wants to take a breather too. So, on Turn 4, we rest. By the end of it, I'll be back down to +27 on the heat-scale.
In BattleTech-scale, I've moved just about 3 hexes total (two forward, one back) and fired an AC/5, a Large Laser, and two Medium Lasers. to be charitable, we'll say I've Walked as well. When two souls become one, I would have generated +17 heat, -10 HS, for a total of 7 heat on the heat-scale. Sound familiar?
In other words, this is all the same thing, just hyperdetailed. Energy weapons aren't nerfed, nothing is broken that already wasn't in standard BattleTech rules (because **they are the same rules**) and the God Mode machine gun reaches out to 12 hexes (at their longest, +5 THM range) which is a +0 or +1 THM for nearly every other weapon in the game.
I get that hearing "Your Warhammer just built up 80 heat for firing its two PPCs" can be mildly disconcerting. The smart MechWarrior will then spend some time evading and setting up some advantageous physical altercation instead of getting silly and keep driving it ever upwards. Because after three more S7 turns (four, total), you'll only have +8 Heat on the 'Scale, just as you would have +2 in BattleTech.
The Heat Scale is there to be ridden like a roller coaster, not feared like a wild mustang. It's a tool like anything else in this game.