If I add the reduced offhand but not style bonus the outcome is not that much different using real weapons (sorry razzer, but you forgot to think of the fact that people do not use same offhand as mainhand spd).
Then the bm/merc will begin to outdamage the berserker at 20% bonus, or 67,6% total offhand swing.

If the passive bonus is 25% then bm/merc have an overall potential that is 3% higher than a berserker.
I really find that hard to believe to be valid.

Look at how Uthgard is as an example.
Berserkers have no defense, while merc/bm have shield, r5 and native defensive abilities, merc even have chain.
If the berserker engage the merc or bm while in frenzy, all they have to do is throw their native abilities or r5 to completely nullify the benefit of the berseker now killing his own defense in an attempt to do damage.

I always had the belief that a berserker had no defense because he natively had a higher damage potential than the other light tanks.
With 25% base bonus to offhand chance to swing, that just is not the case anymore.
The berserker would now have less damage, and less defense compared to the other realms counterparts.
I would really have a hard time swallowing that.

The base damage was equal on live between LA and CD actually, so long as you had at least 51 composite left axe (to cap your offhand weaponskill), without factoring the haste effect, and just slightly higher for LA when you did factor in the haste effect.

Style damage is only varied because the growth rates are not mirrored, so whoever uses the higher growth rate gets more style damage.

With haste effect, zerkers did do more damage on average, its just that the likelihood of CD/DW over performing the expected amount of offhands in small data sets tends to be greater than the likelihood of CD/DW under performing. However, when it does under perform, it does so by a greater amount of base damage than when it over performs, and the overall base damage is the same as LA when looking at all data together (ignoring the haste effect).

The berserkers real advantage in DPS was zerk mode, 2H + celerity, though 2H is fking useless for DPS on uthgard without defense penetration.