Hi stevef624,
Urban Mattress must have recently opened their store in Vienna. I already had them included in the list for Austin and in the Denver, Boulder, and Fort Collins area. Thanks for letting me know 
I’ve added them to the list of better options and possibilities in the Washington DC area in post #2 here.
All of the PLB, Urban Organics, and Savvy Rest mattresses use good quality materials. The differences between them is in the type of latex, the amount of latex, and of course in their designs and the flexibility to make changes either before or after a purchase. Savvy rest has a modular design which allows a lot of flexibility to either re-arrange layers or exchange a layer to adjust the feel or performance of the mattress. It also allows you to replace just one layer instead of the whole mattress if the top layers softens before the rest (which is usually the case with all mattresses). Unfortunately they are significantly more costly than other mattresses that are almost exactly the same in terms of materials, design, and flexibility so the local premium for a Savvy Rest vs an online purchase is significant. Whether this kind of premium vs other mattresses that use the same or similar materials is worth it would depend on each person’s personal value equation.
Your own careful and objective testing along the lines of the guidelines linked in post #1 here (which also includes all the other basic information, steps, and guidelines you may find helpful) will also help you decide whether the extra cost of one mattress vs another or one feature vs another is worth it to you.
Phoenix