Three 4+ shots are roughly equivalent to two 3+ shots, so 2 Toulon have the gun firepower of an Osaka. They have smaller sigs as well and more CAW, though the Osaka is tougher is a lot of ways.

Somewhere on this forum there is a lot of discussion about lasers vs guns with the math and expected damage. Suffice to say, cobra lasers are much more powerful than mass drivers.