Not everyone who bought a Lumia 930 has had issues, so I don't think you should be all that worried.
Hopefully yours will be fine.
May I ask, why are you leaving your Nexus 5?
I'm not 100% sure that i'll leave my nexus 5. My reasons are mainly subjective. I always loved the style/design language of WP and the synergy with Windows PCs (i think microsoft now begins to extend this synergy).
But maybe i should wait till WP 9, because my nexus 5 is still fine .. dont know .. need new toys ;D