So why does hardly anyone use it now? I still play tf2 nearly everyday and it's very rare I see a scattergun and like I said I've did a test where 6 shots of scattergun did less damage than FaN shoot/reload 3 times. Plus FaN knockback is very useful against heavies.
It's well known that the scattergun is actually a much better weapon than the FaN.
The only thing the FaN is useful for is having a laugh with the knock back or utilising the utility that the knock back brings.
For actually killing things effectively just put on the scattergun and be done with it.
Just because in 6 shots one does more damage than the other does not make it more effective at killing.