You're looking for ways to diversify weapons? I have a really good idea for PPCs. Yeah, they look cool, have high heat and do nice damage, but they're really just a long range, accurate weapon currently. They have nothing that really defines them as the weapon we all know they're supposed to be - screaming hot lightning throwers. They should feel very powerful, but difficult to use. That difficulty is in handling the heat.
They are described in lore as being weapons where firing even two of them simultaneously is something that is pretty hard to bear for mech pilots, with three being almost suicide (Awesome pilots are braver men than I), and four? Well... double heat sinks are fairly new technology again, and I'm not sure I'd personally risk it until the tech improves a bit more. Even putting lore aside, it's how you've been balancing the weapon already, distinguishing it with that fact. So, my suggestion is to distinguish that element further... Make it the only weapon with ghost heat. It's a unique, interesting mechanic that increases the heat of using that weapon in groups, which makes perfect sense for a weapon that is supposed to be very heat unfriendly.
Personally, ghost heat never made much sense on any of the other weapons (except maybe AC20s). Also, the line of how many weapons it takes to cause ghost heat always seems to land in weird places (LRMs are stackable in ways which make equal missle counts cost different amounts of heat), and the system is still bugged in a few places (AC/2s have weird chain fire heat). I like the idea for ghost heat as a mechanic, and it works great at preventing larger numbers of PPCs. But it doesn't make sense for a lot of the other weapons.
Now, there are a few other places where it does its job well. AC40s are slightly less common, though such builds usually had their own issues anyways. I presume the SRM limits were in anticipation of the buffs they've been getting since, and LRMs are always spiking between OP and UP among the general populace, so it couldn't hurt to have the ghost heat for future 'OP' times. However, these all could have been fixed with other, smaller nerfs that are easier to understand for their respective weapons. I won't go into any of those here, but ghost heat just feels odd on a lot of other weapons, and kills more valid builds than OP builds it prevents. Plus, it seems the perfect way to distinguish PPCs and ER PPCs. Only downside is that it's a bit more work to re-balance a few of the other weapons that might be a small bit stronger without it.
Edited by Tvae, 03 September 2013 - 04:51 PM.