Upon reading the comments made by both of you, I would say that none of you knows how the SA Crit DMG applies. First of all, there is no JAVA server where the SA Crit DMG works at all. Here, I would say that there is a difference of DMG comparing the DUAL dager and CD one - 150 dmg max. The SA Crit dmg says - Adding P attach when Skill is applied. GM mentioned that SA dagger in oly is better but not because max Critical is reached with buffs. The reason why SA dagger is better to pvp without buffs is that the SA effect is lowered by the following buffs - Chant of Protection, Eye of Paagrio, Counter critical and PVP Armor. In oly, most of the time the players you are fighting against are lacking these buffs and you can feel the difference.
In addition, I would like to mention that PVP dual dagger for oly is better only vs TANKs or BISHOPs, cause of the cancel effect.
And last but not least, the skills usage with single dagger is faster than the dual dagger. Not to mention that the Dual Blow has a huge cooldown. Let's do the math:
If Dual Blow deals 2k dmg, before using it again, you would have used all your 3 blows x 2 times. If the difference in the damage between the SA and Dual dagger is 200. This would result in 1200 DMG in total. So I would say there is a slight difference in the dmg, but the animation with the SA dagger is way faster than dual dagger.
Overall, in light of the above said, I prefer and also play with SA dagger.