M&P .40: From what yr/serial prefix should I get

[Rayden]

I am planning on adding a M&P .40 to my stable, and possible carry rotation. I've heard about (whether true or not) that the earlier batch of M&P .40 had some kinks that were eventually worked out for the later production batches.

With that in mind, do I need to be concerned about any year and serial prefix I need to avoid?