AM-SAR is not OP, you just listed every automatic weapon in the game, flak generates a metric buttload of heat to compensate for it's burst damage. Plus, if you miss, you'll overheat faster than.... cakes
The one and only time I overheated was in a Reaper. This was some days ago.
I played Flak Scout, Flak Brawler, AM-SAR Reaper and noticed, DPS, Burst and overall stats are way better than for example EOC, Heat, Slug, etc.
Players who overheat with these very very low heat generation (except Incinerator) are really doing something terribly, extremely terribly wrong.
I myself missed like 50% of my shots in a Reaper, which lead to an overheat.
Heat generation is no argument since it's basically not even there.
And my problem with the Flak is:
1. Burst damage as high as its DPS.
2. No charge required, allows you to boost, dodge while relaoding (replace with T32-Bolt).
3. Easy to use, you don't have to aim properly, you can half way miss your target and still deal a good amount of damage.
The proble mwith automatic weapons:
1. No recoil
2. Way too less Heat generation
3. Accuracy remaisn stable while in mid air due to no recoil.
4. DPS almost as high as the most burst weapons -> 1 sec DPS equals one FULL burst load, too less.