Yes, it's 'open' -- not arguing that, nor would I dispute that Mono is far from perfect. [1]

But, like so many FF projects: is this the cart, or the horse?

In other words, this feels more like a promotional project for the consulting firm and its pay products than it does a 'real' project. I freely admit this judgement has some external bias; Jon H. has a reputation.

[1] footnote: (Of course, neither is the linked project... 128 bits for each and every pointer on a 32-bit architecture? Does that mean 256 bits per pointer on 64-bit? Yikes!)