This is an interesting change. The text on Dooku's ability "Surely You Can Do Better" was actually changed. The new text is as follows:
When a character in this Unit defends, during the Modify
Dice Rolls step, this Unit may spend 1-3 force to use this
ability. Change one hit result to a failure for each force spent.
So how does it compare to the old one?
Well, this seems to be mostly a timing change. In the original version, you would have to spend the force before the dice were rolled. Meaning that your ability could hit nothing, which would be very bad as you could be spending three force on it. With the new ruling, you spend the force after the dice have been rolled. This way, you know the results already and don't have to waste force on an ability that wouldn't do anything.
I think this is a good change, making the ability more useful instead of having to gamble on the amount of force required.