I bought six new 45 Shields, fired them all (mostly just four or five magazines), all dated from November, 2016 right up through March 2017 and I have never had a mag drop. All had the "old" un-grooved followers.

However, that doesn't mean YOU won't have a mag drop.

I just set up my Dremel drill press and stone and ran all my followers through to create the groove just like the factory's "new" follower (which I shook down S&W for and used as my model).

I think the mod of an "old" follower or asking for a "new" follower is the safe route to follow with the 45 Shield. I have had enough OTHER bad luck with them so there's no need to leave any stone unturned in my experience.