I agree the chaingun feels a tad unresponsive and difficult to control. I think this comes down to the spin-up stage, which is too short to be used as a lower-rate crowd control, but not responsive enough to be used as a "sniper" or in short bursts, because you need to wait for the spin-up but the zombie is dead by the time the spin-up finishes so you just end up either wasting rounds re-targetting, or stop shooting while targetting and need to wait for it to spin up again on the next enemy...
it could be improved a bit by having the spin-up and cool-down take longer with some kind of inertia, so it's possible to "ride" the trigger (hold-release-hold-release) for a more moderate fire rate, while still allowing the possibility of holding down the trigger for the full-bore boss-slaying dakka fire rate. I feel this would make it more effective against midsize trash crowds, which was the chaingun's original purpose but kinda gets lost with the redesign.
Compare and contrast with HD's Vulcanette, which is viable to run-and-gun with on "fuller-auto" because it's so responsive that you can just long-tap and near-instantly get 5-10 rounds on a mob, which is just the perfect amount of (over)kill.
