Dual Blade Builds

I'm only deducing that tornado spin is worth getting based on the fact that a level 163 in non-tespia kMS is using it, and I would assume by that level, he would know the best way to train at oblivion 4 =|

Flying assaulter probably has a delay or something, so tornado spin would provide the extra rush in that delay that you can't get from any other skill.

Four people play that account, with 6 hour shares each. It's not only one person. So their experience with the class kind of varies.
You're right about the delay comment, it would provide an extra rush during the time.