If you want an alternative loadout that can manage swarms better and deal with High Value Targets equally, then try this: https://karl.gg/preview/17079#/
Even then, you can still use the Cryo Grenade for it.
I'd argue though impact deflection is good, it's not as outwardly OP as TEF (providing 12+ fire damage per individual bullet for essentially no downside). Double barrel also simply fills a separate purpose of close ranged wave clear/single target, while this Boomstick specializes in ranged HVT/High Priority denial from long ranges or during uplinks, so it's really comparing apples to oranges I feel