>>... most of the recent innovations in Solaris's core technologies (DTrace, ZFS, Zones, etc) have all happened in illumos.
> As a core Solaris dev at Oracle, I can tell you that's not true. I just can't prove it to you. :-(
Among the more interesting topics Roch wrote about were some enormous changes to arc and l2arc, the zil, encryption, spa_sync, sequential scrub & resilver, which LBAs to choose when writing, and scalability of rw locks. OpenZFS is still reinventing several of these (e.g. sequential resilver and persistent l2arc are in github PRs now) albeit in generally very different ways.
If he is able and willing to participate in OpenZFS development, the whole project and its close relatives (e.g. ZFS on Linux, OpenZFS on OS X aka macOS) will benefit from his having explored the invention and development of similar wheels.
I do not know if he is still with Oracle. Either way, if you move quickly, the blog is likely to survive until after Labour Day.
(Someone should archive it for posterity!)