I would bet that they have. Personally I stopped using eBay because of sniping. I'm a particularly devastating case for them, because had the system not felt rigged to me then I likely would have continued on the site making many purchases. However it immediately made me lose confidence in the system and bail.

Unsure (those reports I read were some time ago). Though that may be another reason why the built-in snipe-like tool was added, so appease those users as well as to decrease the load imposed by external tools.