I try to keep my expectations in check as to not overhype it up and set myself up for a disappointment, but even the most conservative estimations of full S11's buffs are pretty damn crazy.
The 60% CRIT DMG she gets from maxing out her Potential and doing her parry (30 seconds uptime, should be up virtually always) is already a raw ~20% DPS increase for baseline CRIT DMG of 200%. For lower baseline CRIT DMG%, it's more.
That assumes 100% CRIT Rate of course, but now that your build gets 60% extra CRIT DMG% for free, prioritizing CRIT Rate and maxing it out should be pretty straightforward.
Additionally, BA5 at its very worst seems to be the replacement for the underwhelming BA1 and BA2 during Harin's burst rotation, as it shortcuts directly to BA3, and it seems to be slightly longer than the two combined, but very marginally so (not to mention, that the player might just be taking too damn long to continue the BA chain).
Not only BA5 has considerably higher damage MVs than BA1 + BA2, it has more of everything
Comparison :
BA5 BA12
Damage 411 .4 225 .6
Daze 168 .2 79 .1
Energy 3 .841 1 .764
Decibels 29 .3425 13 .5025
Anomaly 106 .66 48 .96
Miasma 106 .67 48 .98 TWICE as good as BA1 and BA2 put together.
Not only does it mean shorter, thus more consistent combos, it also means that for the same time spent on the field Soldier 11 would generate more Daze, build more Decibels, apply more Anomaly, gain more Energy, and even purify more Miasmic Shield.
And the estimation for Damage specifically is extremely conservative, because the most likely intended multiplier for BA5 would include the Explosion damage as well (which I don't think works right now), putting it either in the
>619.5%~722.9%
range being conservative, or
>619.5%~982.2%
if they decide to go crazy with it.
For reference, BA4 (the final hit in her BA combo currently) is 681.7% damage MVs.
On top of that, DC getting Dodge Offset functionality means on average Harin's MVs out of stun get increased quite dramatically.
While during the stun, you get more BA4s every burst rotation because EX, CA, and Ultimate all shortcut to BA4.
Oh, and I'm pretty sure, her BA combo does go faster if you time presses while you have automatic Fire Suppression charges.
Looking at it extremely conservatively, and assuming these massive BA improvements result in no more than 15% average DPS increase, still land us at 38% total DPS increase from the buffs.