Similar circumstances.
I am only staying with OS X 10.8.5 and OS X 10.9.5 to use all of my older Apple Software reliably.
I STILL use iPhoto, Aperture, iDVD, iMovie '06 HD ( the only true and really great iMovie version Apple EVER created), Logic Express and Final Cut Express.
All of these run terrific on OS X 10.8.5, but iMovie and Final Cut Express can flake out for no real reason from time to time on OS X 10.9.5.
I end up saving work more often in these apps in OS X 10.9.5.
Unfortunately, I am finding that I am having to use OS X 10.9.5 Mavericks more for the more recent programs I am using that are only Mavericks and later compatible and having to move away from 10.8.5 Mountain Lion even though ML has been rock solid for most of my older apps and some of my current apps that are the same ones that I use under Mavericks that, somewhat recently, ended support for OS X 10.8.5 Mountain Lion.
I hate the idea of booting back and forth between systems, but I may just resort myself to doing this seeing these are the only versions of OS X I have to stay with and use.
Technology. "LAWTS' of fun!