As a general rule, you should always download the security updates and Defender definitions. I would also recommend installing updates for Windows, as these are improvements/fixes tied to the OS (but you can pick and choose the ones that you think apply to you if you're concerned about it). The ones we talk about in here, and recommend proceeding with caution, are the System Firmware updates. IF your device is working to your satisfaction, I would suggest not downloading the firmware update. If you're having the issues listed in the fixes provided by this firmware, and these issues are seriously impacting your enjoyment or productivity with the device, then yes, do download the firmware update. I chose to do so, as I was having issues with the keyboard and battery meter, and these have indeed been fixed on my device. I have yet to experience any new side effects, though I'm still experiencing some of the old ones that have yet to be fixed.