ER Large has larger Short and Medium range brackets than the PPC, and it has no minimum range.
The funny thing is that the ER Large's lack of minimum range is much a hindrance as a help. Why a hindrance? Because if you're like me, you like mechs that bracket fire. In bracket firing, certain weapons are used for one range bracket, and other weapons are used in another bracket. Typical example is the PPC and medium laser. PPCs are used until the enemy gets inside the minimum range. Once inside the minimum, you switch to the medium lasers because it now has the better TNs, thus you only need just enough heat sinks for the heat generated by your hottest weapon set.
The ER Large doesn't do that as well because unless you're using pulse lasers as your close in weapon like a Penetrator, the ER Large will have the best TNs from long range all the way to point blank. Therefore the ER Large and its 12 heat should be in every weapon set used at all ranges. That's 12 heat sink capacity that cold have otherwise been dedicated to a more powerful weapon set.
Okay sure, a little fire discipline would let you use a set of short range weapons without overheating, but I like having a minimum range to enforce bracket fire discipline. Call it personal preference if you will.
Plus, I prefer 10 damage to 8 too. Having a round two digit number is psychologically more satisfying than a single digit number ;)