I purchased one, but can't tell much of a difference. I think it depends a lot on your water supply though.

Actually, since I remove every 4 days or so I don't often shower with the piece. I wash it in the kitchen sink under my drinking water filter.

But I say if you're gonna wear you might as well buy one unless your water comes from pure mountain streams. It's a cheap little bit of insurance, and I'm sure it does help to an extent.