I bought an SXP defender in 2010. A 50 cent plastic part failed less than 1 year later, making the gun unable to reliably cycle any rounds. I contacted winchester's customer service department and they told me that SXP parts were unavailable. I sold it to a gunsmith for about half of what it was worth. Maybe they've stepped up their game since 2011, but I doubt it. The SXP's are a pleasure to shoot with a very fast action, but the defender series is/was a TERRIBLE field gun and the customer service I received was unacceptable.
Buy one from a dealer that you know will help you out if something goes wrong.
Furthermore, the field version of the SXP's have experienced a spate of recalls for being mechanically unsafe.