ZFS boot support didn't really have a bearing on scaling up large FreeBSD storage servers. It is standard practice for various reasons to have a seperate RAID

ZFS boot support didn't really have a bearing on scaling up large FreeBSD storage servers. It is standard practice for various reasons to have a seperate RAID (or SSD) for booting large fileservers. OpenSolaris had so many restrictions on the boot ZFS pool (could only be a single disk or RAID1 mirrored) anyway. It is ironic also that you mention driver availability, when driver support is one of the problems with FreeBSD. Commercial support has been quietly but steadily eroding for the last few years. If you try to put together a big FreeBSD system, as I have done, you start to run into trouble once you leave the lower levels of consumer-grade hardware. If you want a viable alternative to OpenSolaris, look at Nexenta. They have recently hired some of the people who left Sun when Oracle took over.