The TDR-9S got a huge nerf(probably deserved) to it's ER PPC quirks, it had 50% less heat gen when you had those equipped, now it's only 25% for ER PPCs(combined Energy Weapon and ER PPC specific quirks).
So i'm guessing that's why Stalkers became so prevalent among IS forces. I'm a little annoyed that they changed the BNC-3M's quirks from the Large Pulse Lasers to something completely different right after they introduced its Champion variant with all those LPLs, kind of defeats the point of building that Champion to use the quirks if you're changing them the next patch anyways :/