May I ask why? Bad work-life balance? Bored?
The other opportunity is with a startup, so quite different. Whilst i'm under no illusions regarding the politics, i'd be able to focus more on the tech and move more quickly with it vs where I am now. The base pay is surprisingly similar, albeit with no cash bonuses in the first year, but the equity on offer 'could' amount to something significant in a few years.
If offered, i'll probably jump. Should the startup crash and burn (quite likely) I'll have hopefully learnt some new skills and can always jump back into $(large_org) later on.
Feels like time to roll the dice...