i use them and a lot, it's just that in 1vs 1 a 6 pounder does it's job just fine as it's a fantastic at gun, i generally use the FF when i expect panther or in team games
Spoken as a peak example of somebody who has only ever lost tanks to a Firefly, and never had to try and use one.
they are really strong at vet 3 when they get the damage bonus and take one less hoot to kill tanks
btw u speak as a peak example as someone who does not play COH2 cause u know that most engagement don't happen at 60 range and ff has better pen than other TD at 52 range already