Hi TazaMax,
From the Method point of view, there really shouldn't be any issues with upgrading from QuickBooks 2012 to 2014. As long as you are using the same Company File, the process should be smooth. If for any reason your are also switching Computers to run QuickBooks, you will have to Reset "Computer to Sync With" from the QuickBooks-Synchronize Tab. Also, if for any reason you change the QuickBooks Company File name, then you would also have to press the "Reset" button beside "QuickBooks file", located on the same tab as mentioned above.
If you have further concerns about upgrading from QB2012 to QB2014, I would advice you to get in contact with Intuit. However, if your post here is simply just making sure Method doesn't have a problem with you upgrading, it should be a smooth process. I hope this helps.
-Ben