I had to adjust the toe-in slightly after I removed the cover on my S-2’s.
That metal grill does nothing good except to keep fingers away.

Mid & Woofer grills off for sure. Tweeter grill stays .

Well, that interesting.

Im using Focal Sopra no.2 for 4 years now and always have the grill off everytime i play it. The grill is hard grill so is better to have it off. For the tweeter i never take it out.