I've been thinking about it for a bit and I do not see why on the recommended Rogue25/Fighter5 build in the compendium, Dirty Fighting is not being maximised.
A rogue with Grip of Night does 1d6+strength+enhance=3,5+5+4=12,5 average damage per on hit on non sneak attacks. (Not counting essences which are blocked in PvP)
Adding 6 damage from Epic Weapon Spec makes it 18,5, still irrelevant damage.
Furthermore, the typical human build has 47Ab, for one round after leaving stealth, 45 afterwards.
So as a Rogue, I see 0 reason to trade hits with anyone. Less damage, less ab, less crit range, less crit multiplier.
It's either Sneak Attacking, or looking for the next way to get the opponent flat footed.
Rogue's damage output is about 80% dependant on Sneak Attack, which implies flat footing. So, I do not see why the recommended build does not maximise the ability to flatfoot through Ditty Fighting to play around the actual source of damage.
By taking SF+ESF Sleight of Hand, Opportunist (+4), and Skirmish Maneuvers, one can obtain +4DC on Dirty Fighting.
That means giving up Epic Weapon Spec + Weapon Spec + Skill Mastery + Slippery Mind.
(I can't check my sheet right now but I'm pretty sure I was able to retain Skill Mastery somehow; Slippery Mind is not very valuable since one can reach 36/37 Will comfortably)
If one pushes SoH to the highest, it is possible to reliably reach 108 self buffed, which means 39DC Dirty Fighting.
Which means that you get a much higher chance of flat footing people and landing your damage with Sneak Attack.
This recommended compendium build can reach 33+14+22+10+6+2+2=89 SoH=34 DC Dirty Fighting. (35 if Enchanted Gloves of Skill are used)
Is there a deliberate reason for choosing 6 flat damage over the enabling of 13d6 Sneak Attack and the AC reduction of flatfooting and the tempo swing of blinding/daze, allowing to squeeze in a silver bell, a gate, a breach...?
Simple math shows that EWS gives a 11% damage increase on non-crit sneak attacks, and a 50% damage increase on non-crit non-sneak. Assuming you can hit someone with 45ab.
Landing a non-crit sneak attack is a 350% damage increase compared to a non-crit non-sneak. And you are hitting on a flatfooted target, which is a significant AC loss for them.
One Sneak Attack deals 13d6=45,5 average damage. This is about 7 times the damage from EWS.
And when you flatfoot someone you get at least a flurry of Sneak Attacks.
(These arguments are neglecting critical hits for the sake of simplicity)
It seems like a no brainer to me.
Am I misunderstanding something ?
Please, sneaky companions, enlighten me.
Addendum :
At this point, if one drops EWS, might as well drop Improved Critical and take Use Poison and sit in Choking Powders recklessly ? Also allowing never getting hit by poisons on 1s.