Nope, they changed the calculations in 3.3/Mod4. Metamagics are now additive. Static boost percentages have always been additive.
The best result is 60 (max base) * 1.9 (enhance + potency) * 2.5 (max + empower) * 2.75 (max crit) * 2 (vulnerable) = 1567.
However, my example used Fireball, but my point was that due to the fact that mobs are superbuffed to compensate for insane melee boosts, a 240 damage spell didn't kill a mob in a level 4(+2) quest. The reason we instakill everything is because that's the only viable option versus such high HP mobs. What caster in his right mind is going to risk ****ing off a bunch of mobs with a lot of damage but not kill anything? Unless I'm goofing off in a low level quest, not me!