For my primary phasers, i would always use the Fast Phasers, but for arcs where i just wanted to have them covered, but didnt want to be facing that way all the time, like the Port and Starboard Side Arcs, i would use the Slow firing. It gives me some extra tonnage that i can put into either a heavier Omni-Phaser, or a Q-Torp instead of a P-torp.
Somethings that i would like to see though, Are faster firing (at the cost of damage) primaries. Maybe make it a special firing mode, call it disable, and make it fire like a Phaser-G did in SFC I and II. Drawback: each time fired a seperate to hit check is made. The plus, if it hits a weapon harpoint it does full damage to the harpoint that is hit, but only the partial damage if it hits the hull or sheilds or something internal like the Warp Core, or computer.
Two: better weapon arcs: SFC I and II had much better firing arcs, it makes no sense that weapons would lose some firing ability over 80 years, if anything the arcs should be wider.
Three: Hardpoints are still too strong, most primary weapons can take everything but a Heavy Plasma Torpedo and still function. Make the weapon hard points weaker, and also, if the weapon is reduced to zero health, call it destroyed, no repairs except for at a starbase or planet. And make weapons cease to function if they were reduced to red. Its too hard to disable ships now as it is, and if you knock out an annoying weapon system, the enemy can have it back online before you can get their second one offline completely.
Four: add the Warp Nacelles as targets, if they are dropped into the yellow a ship can no longer engage warp until the nacelle is brought back online. Think of it as a permanent Tachyon pulse if the Nacelle is put into black.