After [4]6S aren't you at negative frames? The throw OS will make them block it, if they are doing it right. After HS [4]6S Leo can be CH'd by a lot of moves, if they IB.
If you use the 6HS loop, after your 5[HS] > D, it's an easy throw.
5[HS] has to be spaced at nearly max range for the throw OS not to work, and in that case it's also not that hard for the opponent to see they they are not close enough.
After testing, 5K cS 5HS delayed flashkick will beat the OS everytime, tho. But then, it's the riskiest option...
I'd rather use the blockstrings RentalBlackout mentioned and use 6HS on block more conservatively.