The only issue with equipping a lot of energy weapons is that each energy weapon firing at hte same time reduces the damage of your other energy weapons by virtue of reducing your weapon energy levels.
That mainly applies to beam boats though, I think it was something like firing 8 beam arrays at once will do less damage than firing only 6.
One thing to note about an all-energy build, is the fact that your weapons consume energy from the left to the right in your slots.
EG: If you have a DBB in your far left slot, followed by a DHC one slot to the right, your DBB will consume the energy from weapons power before the DHC does. Therefore, the DHC would get less of a punch than the DBB. AFAIK, this runs true for aft weapons as well.