I may have more time to do other things but there are a lot less tangible benefits to Stack Overflow that I would find irreplaceable.
For one thing, I am exposed to a much larger community than through any collection of blogs or books I read. With blogs and books, I tend to pick material which is within my specific areas of interest or comfort zone. With Stack Overflow, I am almost forced to be exposed to a much larger body of ideas, alternative approaches, and even languages I would never have looked at otherwise. That is by design.
I have significantly honed my writing, teaching, and critical thinking skills. Normally, you learn something and you think you pretty much grok it. But try and explain simple concepts to someone else and you really learn something. Add to that, the answer-fast-accurate-and-complete element of Stack Overflow and... that is a priceless skill. It has been invaluable as a developer, a mentor, and many other areas of my career.
I continue to learn a lot about the way people work, think, and work together. "Community building" has long been a focus and sweet-spot in my career. Watching a new communication paradigm (Stack Overflow) emerge, develop, and evolve from day-one has been an invaluable experience. That translates into my development skill set as well; learning a whole new dimension of user experience, usability, and interface design. The social aspect of watching how people work, think, and solve problems on Stack Overflow has been like attending a 24-hour/365-day virtual technology conferences and trade show.
So my free time may go up in the short term, just doing the same-old, same-old. But my experience here has added significantly to my domain knowledge; in both "how many" things I can do and how well I can do them. All a net benefit.