When it comes to bumping, each airline has its own rules & policies, so we should be careful of generalizations like "elite status doesn't matter" in choosing which volunteer to select. Whether you can split the voucher, whether you can get a 2nd voucher for the unused balance, whether the ticket bought with the voucher earns miles, whether the voucher is even a $ amount or a round trip amount...all depend on the airline (and possibility the volunteer's negotiating skills). So the best advice is to familiarize yourself with the policies of the airline(s) you fly most often, and decide which policies are most important to you and get those answers before you surrender your seat.