Maybe some scenes could use a "comment" from one or two Stormies, but an the whole, I would leave them silent, that makes them a quiet, brooding force, that is only unleashed by their "master" Darth Vader ;-)
The only audio issue I got, is to have Boba Fett talking in his original voice - it is kind of strange to hear "Jango", I always liked that raspy old tone, combined with the spur sound (though he obvious got none) to mirror a Eastwood/VanCleef bountyhunter guy ...