Lotta ppl getting upset in this forum lately... The game is as close to balanced as it has ever been, now a lot of IS mechs are on par with their Clan counterparts thanks mainly to LFE. The Clan XL Engine is still superior to LFE though.
Ultimately Clan weapons are still superior because of 4 main reasons: Damage, Range, Tonnage and Crit Slots, every Clan weapon is superior to it's IS counterpart. Every Clan weapon is suited to just about any occasion, whereas IS weapons are role specific, for example the Clan ERPPC does everything that the 5 different IS PPC's can do combined, The Clan ER lasers are still greater range than the IS counterparts.
The Heavy lasers are just downright deadly as they are, to reduce their duration is folly, they are the first attempt at making role specific weapons for Clans, I mean seriously, 18 damage for 4 tonnes?? Yes Please, even 10 damage for 1 tonne is insane!! The heat factor isn't even that bad after trying them out myself, Just learn to use them better instead of alpha poke/pop tarting all the time.
You can't just shove a bunch of lasers on and hope that everything will be fine, balance out the weapons like traditional mechs, take some low heat ballistics to offset the high heat energy, take some LRMs to hit the enemy before you get to optimal range. Don't just alpha strike, fire your weapons in stages, you know you can have more than 2 weapon groups right?
As both a Clan and IS player, the only OP weapons are probably the RAC 5's at the moment, the rest seem pretty good to me for now.
Please note, I am not trying to insult, degrade or attack anyone with my post, merely trying to provide positive advice and thoughts.
On another side note, for anyone who wants a fun mech to play with new tech, check out the BJ-A with 6 HMG & 3 Med Pulse, throw on 4 JJ's and the rest in a LFE. Skill it for speed, mobility and jump ability, then use the rest in range & consumables. You'll thank me later