My biggest concern with Chia, is that Proof of Space doesn't actually "use up" any space. In particular, this means that when a "miner" is faced with a choice

My biggest concern with Chia, is that Proof of Space doesn't actually "use up" any space. In particular, this means that when a "miner" is faced with a choice of two competing blocks (or transactions) their best option is to simply "mine" on both of them. This is doable because, by it's very nature, proof of space has little to no opportunity cost. As a result, it seems that proof of space doesn't really come to any consensus. In particular the Chia software will track up to 5 simultaneous chain tips as a consequence of this. P.S. My understanding could be a few years out of date, so do correct me if I'm wrong.