How is it unstable? The reports I've read are either caused by a bad flash or an issue with Go4/phone/tablet which is unrelated to any firmware.
When I upgraded, it said ok complete, but the first power up I knew it was no good. So I reflashed and it's been golden.
There's a whole lot of complaining that it's DJIs fault that you can't follow directions, or it's DJIs fault that your phone that runs Go4 is crap.
Folk need to remember there are literally THOUSANDS of variables that are out of DJIs control...and that this is an RC hobby. Not everything is turn on and work flawlessly ala iPhone. You need to put some effort into it too.
Their firmware is not without "issues", however it is nowhere near as bad as the crybabies say.