I'm close to that point at my current job, too. I feel like I learned lots, but that the learning and growth has plateaued for me, so it's time to move on. I would love to just announce my leave and head out in uncertain waters, but I have a rule that I always have to be moving towards something I want, rather than away from something I dislike. Leaving because I am unhappy with the work would break that rule (to my dismay).

From one Dan to another (Danny, actually), I wish you luck, and I hope you succeed in finding what you want to move towards!