I'm running FTM 2010 for the Mac on my MacBook Pro using Lion (OS 10.7.5). I get the occasional crash but basically it works fine.
Mavericks, OS 10.9, is due to come out Sept 10th. I plan to upgrade (I am skipping Mountain Lion (OS 10.8) because it's not necessary for the Mavericks upgrade).
Will I still be able to use FTM 2010? Of course no one will really know what will run on Mavericks until it's out, but the information Apple has released and the speculation of experts is that anything Mountain Lion runs should be fine on Mavericks.
I did not upgrade to FTM 2012 because I heard such awful horror stories. And now FTM 2014 is due out (who knows when the Mac version will arrive?). I'm willing to upgrade but I'd rather wait for 2014 than do 2012 right away.
Advice, timing predictions, and voices of experience welcome.