Most Rogues primarily focus on their Subtlety spec as it is the most important spec we can offer in a Single-Target scenario. Multistrike is the best enchant there so many rogues who only have two good weapons will enchant them with Multistrike and use them both for Subtlety and Combat. If you are in the mood for experimenting, try simming your Rogue with all possible combinations of Enchants. Some >745 Subtlety Rogues use Multistrike/Crit over Multistrike/Multistrike weapon enchants because it is slightly better during the opener on some bosses.
@Infinity Thanks for making the effort of a scientific approach. This is the way those questions should be answered.