I have a Lumia 540 which is Primary phone and I am currently running Windows 8.1 update 2 Lumia Denim. I want to upgrade my phone to Windows 10 mobile but am afraid my phone might give me problems after sometime. Is there a stable Windows 10 Mobile update available for Lumia 540?
The latest Insider build is fairly stable, but you're probably best off waiting until it's officially released. They're expecting to start the rollout sometime in December.
The current slow ring is the release that has been rolled out as part of the new Windows 10 mobile devices (950, 950XL) however it will most likely have been tested thoroughly to work well on these devices and as Microsoft haven't announced a roll out to all other Windows phone devices, you may want to wait.
If it adds anything to it or not, I've been running the Insider Preview on my Lumia 920 for the past 3 or 4 builds and it's been fine on there.
Choose SLOW RING and Update to Build 10586.29
You won't be disappointed. Trust me!