I had the power seller logo once, then received a rather " blunt email" from ebay saying they were taking it away (low sales for 1 month)
I noticed after the logo had gone my sales did better ? Then ebay offered to give it me back (sales went up) I felt like telling them to stick it where the sun don't shine !!
They can keep it, I no longer use the icon. As a buyer when I see a power seller logo I tend to skip by them and look elsewhere, maybe that was what was happening to me to with other buyers when I had the logo. So, NO I would not show it.