Shipping must be expensive and the seller could send a perfectly good piano that might get damaged during shipping or the piano might not be what you want. If you wish to send it back, will you have to pay the return shipping fees? Do you think you could resell it locally? Ebay has been notorious for siding with the buyer these past few years. If the seller has a good reputation and there's a way to protect yourself from too much financial risk then it might be worth it.
As I read through this thread I was thinking that I'd do it if the reviews were good enough. But you make a really good point about the potential for shipping damages. That's making me think that I probably wouldn't' do it, especially if eBay has been siding with the sellers.