the worse-case performance of our daily backup (~150 MB per day delta, ~45 GB total post deduplication) was about 40% longer than our typical case
Yes, that sounds about right. I had maybe half a dozen people write to me who had noticed performance problems, and after the initial "backups failed because the server hit its connection limit" issue, it was people whose backups were already very long-running -- if your daily backups normally take 20 hours to complete, a 40% slowdown is painful.
I run my backups overnight and get a status email each morning, and I didn't even realise there were performance issues until now. As you said, unless you run your backups multiple times per day, or have long-running backups, it may not have had a lot of impact.
FWIW, I live in Australia (so an 'off-peak' timezone), and schedule my cronjob on an odd minute offset, so it may not have been an issue for me anyway!
Yes, that sounds about right. I had maybe half a dozen people write to me who had noticed performance problems, and after the initial "backups failed because the server hit its connection limit" issue, it was people whose backups were already very long-running -- if your daily backups normally take 20 hours to complete, a 40% slowdown is painful.