Bitshares 1 seems to be run on poloniex, will they update on version 2 soon??
TetherUSD is used on plo directly but the orderbooks are too thin to exchange really there. And i don't see a full relation to the US-Dollar.
I wonder if bitshares 2 are really better and bitusd? Where do they trade best and what is the insurance on bitusd that they can back the value and don't run with the backing?
At the moment it looks to me like only nubits have the low enough spread and good enough filled orderbooks to use it. Though not really in times of crashes or fast rising prices.
Poloniex upgraded to bts 2.0 last month. Have you read any of the links I posted above or checked out the wallet? The links will answer your questions on what "backs" BitUSD, BitBTC, and all the BitAssets. Check out the hosted wallet by OpenLedger https://bitshares.openledger.info/