As far as "total" losses, luckily there have only been a few, and almost all of those were replaceable. A couple just never 'took off" after planting, and the vendors replaced those. I did lose one of "last years" iris to a strange case of rot, and, so far, I haven't been able to find a replacement....and it's getting late enough in the year that it will be a "next years' project.
I did lose one late last fall, also, but .supposedly, I have one coming to replace it....if it ever gets here, that is ! Again, it's getting pretty late in the year to be doing much iris planting. ..............Arlyn