Zero risk. I haven't faced any issues on my lumia 920 and 520. I am enrolled in dev preview program since GDR3 was announced. There are many users having issues with new OS , but it's still a preview not the final build.
I should have been more clear there , I didn't have any risk (zero risk ) , and all my other mates who are using dev preview program in my collage ( I made them switch to wp 8 and now to wp8.1 ) are enjoying it.I would disagree that there are 'Zero Risks', which, btw you contradict in the very next sentence.
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