I'm doing freelance contracting and trying to build a development/consulting shop partly for the same reasons you gave: I like the freedom and I think it's more efficient and modern, and frankly more adult & unpatronizing. Lets me work when, where, how I want, and unlocks enough extra free time & energy that I can spend more of it on other things like hobbies, friends, family or other enterprises or personal investments. A net-win overall. Not perfect, has downsides. You have to spend more time selling yourself, and there's more uncertainty about your future paycheck stream. And can be more isolating. And this giant spider hunts you wherever...oh wait. Nevermind that last thing.

But seriously, back to your post, if you do take time off to work on your own product, I suggest you don't burn any bridges employment-wise, and maybe set it up as an unpaid sabbatical with your existing employer, with an agreed upon return date. That way, you have the option of returning to them and that steady paycheck if your experiment doesn't get traction. This is more important because you have wife and kid. Also, use tools/tech that are good for rapid development and experimentation (Python, Ruby, etc.), make a Minimum Viable Product, launch/feedback/tweak/repeat, and don't underestimate the importance of marketing & advertising.

Another option for striking out on your own is to ease into it gradually by first becoming a contractor/consultant. The work you do is similar to salary/staff in that you're writing software for other folks, fixing bugs, etc. except you have more freedom/time/control to work on other stuff, like a product/service startup. And you can blur the line by developing a product/service whose design was informed by, driven by common demands from, or was a by-product of, your contracting work. That was the 37Signals route I think, and lots of similar stories out there.