Some of this also ties into why I keep my computerized machines (all 2 of them!) on UPS (Uninterruptible Power supplies - also known as battery backups) as well. They're like a consumer grade version of what SteveH is using in his server room. I have a heavier duty UPS on my servers here as well but while I run a production server (think AA) I don't have / need the sort of infrastructure SteveH is using.
Basically, to my mind - any computerized sewing machines should be treated like a computer. I use UPS' for the computers here and so too the sewing machines.
My LongArm and my new to me embroidery machine are both always on a UPS. That helps keep the input power relatively clean at least. Now if I could just find ALL the outlets that are sharing a circuit with my server so I could stop switching it to UPS when I vacuum or use the air compressor!