I own a 2013 PA-14 since new and I know the only change from '13 to '14 was adding a rudder BOA. I bought a kit to upgrade my '13 and that was an important improvement.
The next change was the drop down skeg. Since that change I don't believe the hull has changed since.
Hobie has been stable with the Mirage drive pocket for the past decade and I don't know of any reason why the newest Mirage drive would not fit the 2014 PA-14.
Hobie has changed the interior for mounting stuff using the track system and new colors have been added.
Basically, it's been a really good hull design and "if it's not broken, don't fix it".