Who still isn't close to presenting the same kind of destruction feats as Enel until the timeskip.
Destruction feats are highly dependable of the nature of the attack, and doesn't necessarily means the attack packs more "strength" in it. In the Arlong Park, look at Arlong' subordinate's destructive power:
http://mangalife.us/read-online/One-Piece-chapter-87-page-17.html
It's a destructive feat greater than most of Luffy vs Arlong, or Zoro vs Hachi for example.
The same can be said about Kaku, whose Sky Slicer had a more destructive force than Lucci's Rokuougan, shattering the high portion of the tower, while Lucci's Rokuougan was just able to scratch through the wall.
Or like Miss Doublefinger attack was able to completely break through the wall, while Bon-clay's Prima Ballerina Swan Bobardier:
http://mangalife.us/read-online/One-Piece-chapter-188-page-14.html
http://mangalife.us/read-online/One-Piece-chapter-192-page-13.html
So destructive feats doesn't kind compare to the amount of damage it will deal to the opponent.
Maybe on equal grounds, but as far as their durability's peak goes, Zoro >>> CP9 based on him taking hits from Moria and Oars whilst still being resilient enough to absorb Luffy's pain afterwards.
It was on Thriller Bark, like you said, whereas Zoro already had got a good deal stronger. But what I am saying is that I don't think Zoro's durability on Skypiea comes even close from CP9's Tekkai, which could allow them completely tank base Luffy's attacks. Based on how a stronger Zoro could deal with Lucci's Water 7 attack, it's highly suggestive Rokuougan is above Enel's top tier attack, despite destructive force showing otherwise.
As I already said, Enel's El Thor showed Town level feats, which is far beyond the destructive power their Tekkai was shown to endure.
And as I showed, those feats doesn't necessarily go hand in hand with the amount of damage the attack will deal to an opponent.