It's a start. An alternate possibility to consider is to make nothing stack at all.
As pointed above, some classes get shafted by this. You should accompany this nerfage with a complete reassessment of how each class is to do damage. Right now, some like Engineers are teetering on the edge of uselessness.
A nice trade-off here would be a top down rebalancing of weapons too. Most of the weapons in the game are not viable choices and revamping them would go a long way towards appeasing the masses.