I am not sure since when the Phaser Lances' description included the mention of a wide beam setting, but can we take it for granted now that saucer separation is incoming?
Because if that is the only upgrade you are giving the ship, we dread jocks will be mightily disapointed.
You can't put a several minute console ability on a fundamentaly broken ship and say "yes its fixed now." - please don't go that route.
Just go the sensible, non-moronic route: upgrade all fedeartion cruisers to match the mobility of th klingon cruisers.
You do not need to give them all DHC's, just give them the turnrate, and rework the modus operandi of beam arays (instead of 4 pulses over several seconds, change it into slow firing hammer blows, 1 shot every 4 seconds. Adjust the damage accordingly. this will fix all troubles base stat wise.).