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.
Updated the first post with the most up-to-date info, by the way. Apparently you can only save 1st to 2nd and 3rd to 3rd+ in the most recent kMS patch (lots of variations about SP saving because kMS kept patching it differently in the week after dual bladers were released).
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.
Updated the first post with the most up-to-date info, by the way. Apparently you can only save 1st to 2nd and 3rd to 3rd+ in the most recent kMS patch (lots of variations about SP saving because kMS kept patching it differently in the week after dual bladers were released).

