Buy the 5yr warranty extension. Yes you can delay updates/make them manual. If I were you and weren't ready to give up the fortinet I'd double NAT it for a while, I think you'll find the benefit of using the complete ecosystem will convince you to give up the fortinet even if there are a few features that fortinet do better.
You can buy a firewall model that has the required controller built in requiring cloud connection or 2nd to that I'd setup a VM using the http://glennr.nl/ scripts as the controller. The scripts are reliable and capable.
I used to run 3rd party, like Sonicwall, firewalls with Unifi wifi for a few years but recent improvements to their approach has made me switch to the whole eco system now and I prefer it.
Sorry, you could be more specific with your title. Was this the one from yesterday? Or the day before that? Or the dozens from last week? Or the dozens from the week before that?