A stalker 4N currently gets 20% heat reduction on Large lasers, the battlemaster only gets 12.5% heat reduction. This translates to 5.25 more heat generated using the battlemaster. The stalker also gets 10% more cooldown and range to the LLs. That being said, it has a few advantages over the 4N. The battlemaster has all extremely high torso lasers. It can also mount an XL engine. If you keep the same number of heatsinks the battlemaster can move at 78.6khp compared to the stalkers 62.9khp I only dropped in this mech twice and this was the second game: Edit: After the patch notes visible on 5/16/2015 it seems the quirks for the stalker 4N have changed. Now this mech has identical quirked heat reduction to the stalker 4N for large lasers.
Thinking about the heat reduction + less cooldown, you're basically just getting less DPS, but techinically less heat. I like it, since you can fire 3 Llas at once for IS mechs. Will try this when I get the 3S! Also you made my OCD happy with full slottage. yersss.
2018 update Stalker is now obsolete and has only 5% bonus to cooldown, range and duration. Battlemaster has lost most of it's quirk, but it does have 6 very high hardpoints (compared to Stalker 4 very high and 2 below cockpit) and a nice -5% eneregy heat generation, which is somewhat more appropriate. There is also new tech: it is possible to downgrade to standard structure, fit light ferro-fibrous and fit a TC1 (my current preferred loadout) It is even possible to fit a Light Engine, but you will lose additional cooling and speed, despite the additional armor Mid skilled gameplay... Not very significant once it has max skills, but it suggest how it could be a nasty pinpointer with 6 LL and good aim.