IMO, the increased heat just pushes all weapon types closer together. Not a fan of that. Instead of making autocannons into just another missile or laser, give them their own flavour. Here's an idea I've kicked around before on Reddit to do exactly that:
* AC/2 does 3 damage, AC/5 does 6 damage.
* Abolish the LB/X autocannons, and replace them with standard AC's. Give standard ACs the increased ranges of the LB/X autocannons. (For units with standard AC/10s, the LB-10X is one ton lighter and one slot smaller. Add one ton of extra ammo on all standard AC/10 designs to make up for this. The others all match, except that LB-X are slightly bulkier, so no changes are needed there)
* Ammunition can be loaded in shell-by-shell, instead of needing to be in full-ton lots. For example, a single ton of AC/2 ammo might contain 10 precision, 5 flechette, 10 standard, and 10 cluster rounds. Caseless and cluster rounds are valid choices as specialty rounds for all autocannons.
* Ultra and rotary ACs can use specialty ammunition if desired, and may mix and match in a single round. In all cases, the shell order is declared, and if only some rounds hit, the first ones in order are the ones that do. They also both get to use un-jamming rules. Otherwise, they stay as-is. (Jam rolls are increased by +1 if using any caseless ammunition, instead of their usual effects.)
This doesn't give them any hugely impressive damage stats, but it gives them more flexibility than any other weapon type. Being able to choose, round-by-round, whether you want to fire standard, cluster, AP, precision, flak, flechette, incendiary, caseless, or tracer rounds is a huge, huge boon to most designs. And it especially benefits the smaller-bore guns that have really deep ammunition supplies, which are exactly the ones most in need of a buff. I might voluntarily mount an AC/3 under this system if I'm expecting a lot of VTOLs or hovers on the enemy team, and an AC/6 is almost good. And it's perfectly compatible with canonical designs, no changes needed.