I understand that the original magazine release on the M&P was plastic and I know first hand that the release on the 2.0 is steel.
The 9mm and .45 Shields I recently purchased have steel magazine releases. I'm wondering if this has always been the case or is this recent and due to mag drop complaints.

My Shield has a plastic magazine release. I thought the unintended magazine drops had something to do with the design of the magazine follower?

I'll have to double check my Shield (2014). But my Compact and Fullsize are poly with a steel insert. Both are 2013.

There are plenty of threads of people complaining about the mag release rusting from perspiration. Perhaps all steel allows for better coating?

Thanks for the heads up. I haven't heard anything about the magazine design. What was the issue and did they fix it?

So are you saying the mag release is ply coated? I'll have to check. I just put a magnet to them and it stuck.
One good thing about shooting south paw is that the mag release is away from my body. Even so, I always wipe my guns with an old CLP soaked rag after carrying one.