I haven't tried the Bitshares DEX. It never came up in my searches. OpenLedger seems friendly, just not enough volume. I'm definitely curious about Waves.

I wasn't sure about the interim units either. I'm not sure why that is necessary other than that is what Atomic Swaps are for. In OpenLedger, it is open.btc, etc. I started by just trading a bit and it seems to go smoothly, so I have been increasing my volume. Everything I can find suggests that all is going well.

If you trade on Poloniex, I know that is not real coin either. They convert when you withdraw.