I love FortiGate's and they have great features and easy to use. I just hate the way Fortinet does their updates. Feels like I am always rushing to update before end of engineering support date for my FortiGates. They said they give you 3 years with support.... not really because you can't us that OS for the first year or sometimes longer because it is full of bugs. Stop pushing new features and give us a long-term stable release that has vulnerability support.
They talked about doing a LTSR a few years ago but I have not heard anything since.