I have various clients that use Quickbooks. There are plenty of things to bash about Quickbooks and Intuit, but it is really an industry standard for small businesses.
I have a client that we upgraded to FMS 14. They have been using 123Sync to connect to Quickbooks and move invoices from FM into QBs, etc. They had been using it with FMP 13 and FMS 14, but it stopped working recently. We checked with Laura at 123Sync and confirmed it is only designed to work with FMP12 and were surprised we even had it working on FMP13. She said it is now a Productive Computing plugin and they are working on making it FM 14 compatible. But for now, we have to make do with FMP 12.
I guess I should have read the fine print on things. But we found out the hard way that FMP12.0v4 cannot connect to FMS 14 files unless SSL encryption is turned off and the files are not Encrypted at Rest. So we had to turn off both of those security features for now unfortunately.
The client is now looking at fmQBO from Geist Interactive and doing Quickbooks Online. They would probably stay with 123Sync, but not sure how long the wait will be before a new plugin version comes out that works with 14 and business goes on and they can't wait to do invoices, etc. I've done one fmQBO solution and may be trying a second one for this client. Advantages of Quickbooks Online is it is in the cloud and doesn't require a Windows machine (this client is all Mac except for this one accounting computer). Being in the cloud makes it easier for them to access from other locations. And with fmQBO, multiple staff can be importing data to Quickbooks or seeing information from Quickbooks at the same time. Also, it seems Intuit has a roadmap focused more on their cloud solutions than PC installed software and going this route may be the better future direction. It would be nice to have the new 123Sync plugin out to compare and maybe see new features in it before jumping to fmQBO. We just might not have the time though.