You can't single out just Felwinters Lie when it's the perks themselves that make it so OP. I have The Crash with field choke, hammer forged, and shot package. Is pretty OP too, though a hair lower on range and impact compared to Felwinters. Point is any shotgun with those perks is basically a one shot kill at fusion rifle range. If no other shotgun could roll those perks it would be unfair but it's a combination that's available outside of Iron Banner, albeit less common since you can't reroll standard legendaries like you can Felwinters.