Currently I have ceramic tile in the main hallways of my house. I am looking to replace this with hardwood flooring and will potentially be performing the demolition work myself to save money. I know there is concrete board under the tile with plywood under that. I want to know, how easy it is to separate the concrete board from the plywood so as to reuse the subfloor (assuming it is in good shape). Is it worth trying to separate it, or just pull it all up and start fresh.
If your question is, "Should I try to remove the backer board and leave the plywood in place?" the answer is, "Yes."
Unless the plywood is warped or damaged, that would be my first choice. It should be relatively simple to pull up the backerboard from the plywood, although there will be a million fasteners.