MBA vs OJT

Realised something nice on the way to work recently - I am pretty much where I want to be (considering the constraints I am facing) in my career right now. I have more skin in the game of business. I am getting paid to learn how to identify, flesh out and set up a new business venture.

MBA = Masters in Business Administration

OJT = On the job training

Seeing as this is what I'm doing (yes, its only been just under 2 months, but it certainly feels like I'm being paid to learn about business), is taking time off to pursue an MBA* worth it? I was already wavering earlier due to the (based on my perception) academic nature of the program. Coupled with it being 12-24 months of no salaried income (another assumption - I will be doing it full time). Is what I will learn in an MBA course worth the opportunity cost? Especially considering the nature of my current job.

Something to think about over the next 1-2 years. One way to potentially structure my thinking about this is to compare what I'm learning now to the contents of Josh Kaufman's The Personal MBA.

*Besides an MBA, I am also exploring a focused Masters on a topic that interests me and could supplement my current experience.