The common consensus is that Flamebreak was nerfed; from 300 burst damage (level 4) to 200 DoT over 4 seconds. Actually each instance of flamebreak damage also procs napalm, and with sufficient amounts of napalm, the new 6.84 flamebreak can even do more damage than the old 6.83 flamebreak.
The damage for 6.83 flamebreak was:
D_6.83 = 75*LvlFlamebreak + (LvlNapalm)*(5+5*LvlNapalm)
The damage for 6.84 flamebreak is:
D_6.84 = 50*LvlFlamebreak + (LvlNapalm)*(StacksNapalm)*(5+5*LvlNapalm)*LvlFlamebreak
If you do some math and rearranging, you'll find that, 6.84 Flamebreak does more damage than 6.83 if:
-25*LvlFlamebreak + (LvlFlamebreak-1)[(LvlNapalm)*(StacksNapalm)*(5+5*LvlNapalm)] > 0
Kind of a nasty equation, so I've plotted it in Matlab.
http://i.imgur.com/axk7rSC.png
The purple lines represents the conditions where the 6.84 Flamebreak does the same damage as the 6.83 flamebreak. With 2 stacks of Level 4 Napalm, Lvl 4 Flamebreak does 125 more damage in 6.84 than 6.83.
In general, Batriders max flamebreak last, with the typical skillbuild of 4-1-4-2 by the midgame. Assuming that Napalm was maxed already, the Right Figure plots the difference in 6.83 and 6.84 damage dependent on the level of flamebreak. Notice -- since Lvl1 Flamebreak only does 1 instance of damage, For Lvl1 Flamebreak, 6.84 will always do less damage than 6.83. On the other hand, as long as you cast two stacks of napalm, you will do more damage in 6.84 than 6.83.
TL;DR, Maxing Napalm first, if you cast >2 stacks of napalm, you will always do more damage with Lvl2+ Flamebreak in 6.84 than in 6.83.