What if the Clans had both the ER versions of their lasers, as well as improved versions of the original IS standard ones as well?
Clan Large Laser: 4 tons, 6/12/18, 8 heat, 10 damage. Less range than a Clan ER Large laser, but same damage and 33% less heat.
Clan Medium Laser: 1 ton, 3/6/9, 3 heat, 7 damage. The range band is the same now as a IS medium laser, but you do the same damage as a ER Medium for the same heat as a IS Medium.
Clan Small Laser: .5 ton, 2/3/4, 1 heat, 5 damage. 33% loss on range compared to the ER Model, but lower heat and still the same five-point damage tick.