Interesting post, but I fear that you are framing the formal vs. informal learning argument as a black and white issue, by using the guerrilla warfare analogy. I believe that the future of informal learning is as a partner with formal learning. I say this because, if I may borrow your analogy, the successful guerrilla insurgency must morph into a formal governing body.

That learning which is developed informally by individuals to meet a specific need should be documented and spread through the entire organization so that groups are not constantly recreating the wheel. If the learning proves usable across organizational lines than it should be documented and formalized.

The key is for organizations to not allow formalized training to become dogmatic and barring further innovation by other groups.