I'd forgotten about my internal flash partition, kept it several versions behind, and was just using the normal one -- and I've spent days working on trying to my my tablet working in the wake of this "seamless" update. The internal flash backup is great. You can use your tablet when you really need it, and instead of reinstalling everything each time the seamless update wrecks your tablet:
http://www.internettablettalk.com/fo...8&postcount=31

You can use the partition installed to your internal SD to make a full backup of your flash-installed partition, and restore it. (fanoush is amazing.) You don't need a full 2gb or 8gb or whatever, either -- my sd install partition is only 1 gb, with the rest for data. If you use your n810 for a job, I'd *really* recommend keeping a backup partition -- even if you don't ever use it normally, you can get at your other data and use it in a pinch.