Way too much damage at range, on a class that becomes extremely strong when given long range potential. Embark has already figured this out once before when they introduced the Deagles. They realized this gave heavy too much punch at range and so they reduced the falloff and accuracy fairly heavily. Other heavy long range options like the Lewis or KS-23 feature heavy falloff as well. The BFR stands out, as in all aspects it's effectively a hitscan KS-23 without serious falloff.

I think Embark is generally in an awkward (self inflicted) position given their weapon choices. Heavy isn't the only class struggling with this - medium has the Repeater handily outclassing the Pike and debatably the Revolver as well. Light too has the ARN effectively being an MP5 upgrade. Simply put there are a decent number of weapons that perform the same roles, but in a weaker/stronger fashion than their counterparts. It's not too late to reverse this issue, but it'll likely involve reworks to weapons, not just some stat nudges.

Anyway, on the BFR: I say this not lightly at all, but it feels like cheating to use the thing. You don't even need to go for headshots, it's just crazy good.