I have a non-critical ZFS pool on an old Dell R510 I like to keep handy. Occasionally disks die, and I feed it spares from other retired boxes I can scavenge. The controller doesn't allow passthrough so it has to be bodged with a load of raid0 as single disks. It's clunky, but it does work.

Every time I do a replacement I have to go through the dance with mfiutil and battle the controller. It always works out in the end, but it always takes hours...