Burg red line backstab broken?

[Findra]

I'm seeing much lower than expected damage for backstab (Surprise Strike crit from stealth and from behind) with my red line build than I would expect relative to my blue line build. My burg is on Treebeard playing Deadly difficulty, currently level 50 (so just hit 35 trait points to enable full trait tree bonuses). For testing, I'm using two level 50 crafted daggers (mirrored ancient steel), no Legendary Items, and generally level 50 teal crafted gear. On level 51 Deep Claws just outside Dolven View, these are my numbers (no reveal weakness, but +1 hope):

Blue Line (mastery tooltip says +165%): 3400 damage
Red Line (mastery tooltip says +290%): 3522 damage (3.6% better than blue line)
Red Line without Sneak Attack (put that point into HIPS cooldown; mastery tooltip says +190%): 2716 damage (20.1% worse than blue line)

So, Red Line with +100% sneak damage and other trait line bonuses for stealth hits is only just barely better than Blue Line. The numbers don't change much when I equip my LI (traceries for crit chain damage, crit chance, and crit multiplier; and Lucky Strike damage). Am I missing something?

[Aranwe]

I'm seeing much lower than expected damage for backstab (Surprise Strike crit from stealth and from behind) with my red line build than I would expect relative to my blue line build. My burg is on Treebeard playing Deadly difficulty, currently level 50 (so just hit 35 trait points to enable full trait tree bonuses). For testing, I'm using two level 50 crafted daggers (mirrored ancient steel), no Legendary Items, and generally level 50 teal crafted gear. On level 51 Deep Claws just outside Dolven View, these are my numbers (no reveal weakness, but +1 hope):

Blue Line (mastery tooltip says +165%): 3400 damage
Red Line (mastery tooltip says +290%): 3522 damage (3.6% better than blue line)
Red Line without Sneak Attack (put that point into HIPS cooldown; mastery tooltip says +190%): 2716 damage (20.1% worse than blue line)

So, Red Line with +100% sneak damage and other trait line bonuses for stealth hits is only just barely better than Blue Line. The numbers don't change much when I equip my LI (traceries for crit chain damage, crit chance, and crit multiplier; and Lucky Strike damage). Am I missing something?

Not unless it's the same thing I'm missing; this problem is the reason I snuck in here tonight.