John, 

The newer AP1 will have a different cosmetic look, but will actually offer slightly more forgiveness and less sole width.

Cameron

1-888-TITLEIST 

I need to replace my AP1 pitching wedge and the challenge has been finding a LH version.

 The 710 model is much easier to find.  Would I notice any playability issues using a 710 PW when my set is otherwise all AP! (2009 I believe; maybe 2010)?

The specifications are exactly the same in the information I have found.  There are "style"/appearance differences; are there other differences that would make sense to keep searching for the AP1 model? 

Just another pain being a left handed golfer.

We just did a manual search and have located a LH original AP1 PW head that can be built as new club.  Please have your pro shop call the Warranty and Repair department.