For a combat sword build and all gear, talents, bonuses, and buffs exactly the same, my RC3 to RC4 buffed DPS went up 18 DPS. The only difference I see on the surface is that my VK has a lower proc DPS (4.78 in RC4) than before (5.11 in RC3). My "Finisher DPS" and "Other DPS" both increased slightly in RC4 with the same gear. My unbuffed and buffed AP hasn't changed (both RC3 and 4 show the same numbers)
Zeroing out AR on both versions still leaves an 18 DPS difference. Weapon skill is currently the same in both. I guess no one else saw a similar difference which leads me to believe one of my sheets is borked or some other change that effects a particular item was altered between revisions.
One of the rogues in my guild said Eviscerate increased in damage by 10% with use. While on a mob that lived long enough to use Eviscerate several times, he noted the skill did approx 10% more damage with each use.
1st Evis = normal dmg
2nd Evis = 110% dmg
3rd Evis = 120% dmg
... how far?
He hasn't tested it extensively though, so we don't know how high it can stack, or how often you have to Eviscerate to keep the invisible debuff active, but he did say he could Sinister Strike/Evis spam and see Evis damage increase as he did this, it did not require a full 5 pt Evis.
I don't recall seeing this documented, or mentioned by anyone else, so who knows? His build does incorporate Imp. Evis and Aggression, it could be an odd effect attached to one of those as well.