Just wanted to give an encouraging word that I at least am following this to see where you end up.

I'm about to start my own journey down this path and I'm debating the merits of sticking with a HW RAID card over ZFS software RAID. I'm also enticed by ZFS but leery of discarding a already in hand HW card. You're build is very similar to the one I'm contemplating with the exception of ECC ram and my plan to use an old Intel X25 I have.