I think the biggest, well "con" I've seen is non-technical - the fear of JAX being killed by Google.
I mention in the blog as well [here](https://neel04.github.io/my-website/blog/pytorch_rant/#gover...) how important having an independent governance structure is. I'm sure for many big companies and labs, the lack of a promise of long-term, stable support is a huge dealbreaker.
I'm not sure how much Google bureaucracy would limit this, but have you raised the subject of forming an independent entity to govern JAX, very much like PyTorch? I believe XLA is protected, as its with TF governance. But perhaps, there could be one for JAX's ecosystem as well, encompassing optax, equinox, flax etc.