On every RT/8 device (including a few Surfaces) I updated (for friends and family), I made sure it had the current updates, including firmware, installed before installing 8.1. Zero issues. If you install a firmware update but don't reboot and finish the install, you're begging for trouble.
Microsoft is so out of touch, they don't even realize that they are hiding the one advantage they have over their competitors: The Desktop and multitasking ability that goes along with it.
agree with JD88. As long as Microsoft doesn't have a Metro version of Office, the Desktop is a great plus compared to Apple tablets. I personally connect my Yoga 11 (RT 8.1) to an external display to do my Office work and it's great. That's the point of a Windows tablet: tablet + windows!