Bumping to put an end to this thread. There were 10 voters who responded.
3 do not use RAID. They might use CARP instead, of course, but I am focused on storage redundancy, rather than system redundancy.
1 uses BIOS-managed RAID.
3 use bioctl(8) to manage RAID controllers.
1 used to use RAIDframe, and has already switched to Softraid without root-on-RAID capability.
3 people are using Softraid without having come from RAIDframe, and don't require root-on-RAID capability.
Two users responded that they were both a softraid user and a bioctl hardware RAID controller user, neither requiring root-on-RAID. I believe my poll was not understood, since bioctl(8) is used to manage both softraid disciplines and hardware RAID controllers. I assume the count of hardware RAID users in this poll is invalid.
I'm the only respondent to the poll who requires root-on-RAID. Perhaps, since no one but me has used it (for software RAID), I should explain its value:
Without root-on-RAID, the root partition must be located on a standard PATA, SATA, or SCSI device. In the event of a failure of that drive, the OS will come down with a panic or a hang. An /altroot partition, if established, can be used on system reboot, but that boot and usage require an on-site admin.