Experience in backorder domains

Has anyone been involved in backorder domains.

From what I understand the domain could be available if the current registrant doesn't
extend and then it goes to auction. I assume that if a certain domain goes to auction the price could go right up but I do get annoyed when I search a domain and it reads that it might be available on back order - either it is available or it isn't.

If anyone has any experience with this I'd love to hear it.