Had to collect tickets a couple of times for away games and no issue. Only one i thought was pointless was having to collect ticket at Palace and then having ticket and ID checked again at the turnstile.
With regards to being able to return unwanted away tickets, what we may find is those in top tiers will buy tickets even if they are unsure if they can go or not in the hope that their circumstances may change as they know they will be able to return the ticket if they cant go in the end. This may mean those in lower tiers may find less tickets available until much closer to the game. May require a limit on the number of times you can return tickets.
With regards to being able to return unwanted away tickets, what we may find is those in top tiers will buy tickets even if they are unsure if they can go or not in the hope that their circumstances may change as they know they will be able to return the ticket if they cant go in the end. This may mean those in lower tiers may find less tickets available until much closer to the game. May require a limit on the number of times you can return tickets.