I think Steempay.io might be working on a US gateway, but for now going from Steem dollars to Bitcoin via Coinbase/Bitpay is probably the preferred route in the US due to regulatory issues and costs. There are other Bitcoin ones like GoCoin/Snapcard and smaller altcoin gateways that could integrate Steem dollars. In Europe, Blockpay.ch uses CCEDK, or you can use exchanges like Bitstamp/Kraken. My focus for my main startup Bitcash (using the Bitshares blockchain to complement the Steem ecosystem) is in payments and so gateways are always the big obstacle. I'm happy to work and collaborate with anyone in this space. Right now I'm content on just bridging to Bitcoin to use their payment gateways and really focus more on product-market fit and traction.