one other important point, BitShares BitAssets such as BitUSD, BitCNY (now used by about a half-dozen Chinese exchanges), and even the new BitXCD (Bit Caribbean Dollar for those to exchange value in the Caribbean block), these assets can't be confiscated, blocked, or frozen from use as tether has just announced for U.S. citizens:

Living in a country known for having some of the toughest financial regulators in the world has its advantages and disadvantages. While it may deter the more cautious international scammers from targeting you it can also hurt your ability to conduct normal business. American cryptocurrency traders are now facing this situation with Tether.

Holders are sent by Tether to exchanges if they want to sell USDT for USD or other cryptocurrencies. They invite exchanges and qualified corporate clients to contact them directly for arrangements. However, the company itself “cannot create or redeem tether for any U.S.-based customers at this time.”

Tether Won’t Redeem Americans, Terrorists and Other Bad Actors