RE-lasers are rather heavy. Using them to counter rareish specialty armors is still mostly waste of tonnage. The buff to the weapons makes 'Mechs with the weapons usable even when the opponent doesn't have specialty armors.
It isn't OP vs specialty armors by no means.
Personally i'd rather have two standard lasers and an ER small laser than one medium RE-laser, even against Reflective opponent, there's always chance of headshots or TACs or some other weapon might've punched a hole already. And let's not even talk about using small RE-laser, you could have three small lasers for one of them.
The large RE-laser is somewhat OK, especially when compared to the large X-pulse laser and its heat generation, but then again the RE-laser bonus is halved. Also a better weapon at distance compared to the large VSPL but that thing is a monster up close. But all in all, i'd rather find another ton from somewhere and get a Heavy PPC, still deals 7 points of damage vs Reflective or (effectively) vs Hardened armor, with better range.
And your still better off than the poor guy with reflective armor at a Missile Convention.
Reflec armor does not have weakness vs missiles.