There's a lot of appeal for the Punisher, there's no doubt about that.
I'm actually going to be developing my own variant of the Punisher for my squadron of three. Well, just for the Command tank in the unit (all my squadron commands will be special variants)
The one I'm going to build will have four of these side by side -
http://www.ebay.com/itm/Dual-Machine-Light-Cannons-2-/262242843269
The design is based on another CIWS design, the Spanish Meroka, which instead of having a singular chaingun uses twelve 20mm single barrels individuallly fed and fired in three-gun volleys for the same rate of fire with a bit more stable firing solution.
Conversely, if you wanted to do similar, you could widen the mantlet/gun mount on your Punisher design a bit and use, say, a handful of Imperial Knight Heavy Stubber barrels in parallel to get a similar visual effect.