Dare I Update My second TNAS to TOS 5?

[Tricky]

I have been testing TOS 5 on one of my machines with somewhat limited success as I have had problems with functionality and have lost two HHD content, but nothing much as it was a test, But my second machine is still running TOS4 and not sure just how long it's going to be supported so wondering if I should update to 5 now? OK, I know I should back up everything and most of it is, but I do have a lot of ripped films that I don't really want to take the time to back up.
My main fear being 1 that I am still not sure TOS5 is stable, 2 I have lost all my data before when I first got a TNAS, it all booted up fine and ran OK while i gradually transferred all my data from another NAS, and then it decided to corrupt everything, and it took me a long time and some recovery software to try and recover just a small proportion of my data, so you can see why I am hesitant about this.