I’ve been using a 5 column version for a while now and have enjoyed it. The biggest issue is that the blackpill controllers aren’t always recognized fist try. It looks like you’re using a different controller- what is it?

Those failure rates are nonsense based on theoretical limits. In practice: a few weeks ago I resilvered a 4 disk z1 array with 8tb disks at 85% capacity in less than 24 hours. I scrub the pool every month and it didn’t seem any more taxing than a scrub.