I think the important thing in regards to SYS and escrow options is that we listen to the market. Right now arbitrated escrow (AE for future ref) is the only option, and that's technically what you're getting in a dark market scenario as well even tho that's not our target market. IF the market shows a large enough demand, we are completely open to adding DDE ~or~ AE options. I'm not going to debate DDE v AE here, as there is an entire thread dedicated to that topic elsewhere, I'll just say we build what people want.
Our next big milestone is really Blockmarket, once that is out and people are able to setup web stores showing only their items, hosted wherever they like, in a user-friendly ecommerce experience I think we will start to see more of the market asking for DDE if that need really exists- if this happens we'll act as needed to address the market need, just as we did with Syscoin 2.1- which includes bug fixes but also a large number of features directly requested by the market in reaction to the initial Syscoin 2.0 launch.
If the people of the community feel strongly about adding DDE to SYS its very easy to make your voices heard- create a new issue on Syscoin github request "Optional Double Deposit Escrow". Post a link to the issue here in this thread, if the issue gets a lot of activity, we'll implement it!