Would it be an option to make it work similar to how @fergish described it? Because if so, I can see a very interesting use case in such an alternative system.
If a SafeCoin would always exist and simply be made unowned when made available for farming, we could have a straightforward system for Proofs of Deletion (or ‘Burn’ if you like) of SafeCoins. Proofs of Deletion are ideal to use in a global general endorsement system.
If people want to globally promote a piece of content, they can put the hash of that content in a SafeCoin’s data field, tell the network to “delete” the SafeCoin, and then publish the deleted SafeCoin’s address (append it to that content’s deterministic ‘endorsement chain’). Until that SafeCoin is re-issued to a farmer, anyone can easily confirm that it was deleted as an endorsement for that piece of content. The ‘decay’ (due to re-issuance) of these endorsements I consider a useful feature. It’d work as a general ‘hotness’ metric.
Proofs of Deletion as endorsements benefit the entire network, because when people endorse something they free up additional SafeCoins for farmers, which increases farming rewards and reduces the storage price for everyone. It also can’t be abused as far as I know, unlike using SafeCoin tips to the author as a general endorsement metric (people could tip their own content indefinitely, so you’d need supervision or a web-of-trust to attempt to mitigate this).
Edit:
This is actually not even necessary, the only change to the current system would have to be that on a farming attempt, the SafeCoin should not exist OR it should be unowned. Other than that the core code doesn’t need to change. Seems like a useful rule regardless of my idea, to prevent permanent loss of SafeCoins (a lot of BTC has actually been purposefully and permanently burned already).