Odd. The tooltip says nothing about any stat increases, just the change of rounds. I guess I should have realized the round itself would have better characteristics. The more you know.
For auto attack (barrage only benefits from the second line):
Reload at vet1 is 6.9 seconds. Reload at vet2 is 3.8 seconds.
AOE at vet1 kills full health infantry in radius 1. AOE at vet2 kills full health infantry at radius 1.6.
Still though, the unit isn't performing like a 480mp unit stock.