Binary Laser Cannon Heat 16 Damage 12 Tons 9 Critical Slots 4
Large Laser Heat 8 Damage 8 Tons 5 Critical Slots 2
2X Large Lasers gets you 16 heat for 16 damage
IMO the 1 ton armor saved mounting BLC is not worth it.
Would an additional heatsink (single or double) be worth it? Another ton of ammunition far an autocannon or missile launcher that you have on the mech as well? Maybe a Medium Laser (hardpoints permitting, though with the 2 large lasers in your example I could safely assume the mech would have atleast 2 energy hardpoints)? Aside from that, the damage of the 2 large lasers is spread a bit and might not hit the same area, the Blazer's damage is focused on one spot (AC/20 vs. 4 medium lasers is another example of this).