Rating: 3 / 5
*Sil-nylon cat cut tarp, elongated hexagon.
*Small and light.
*Can purchase with REI gift cards!
*Use as dining fly or windbreak for 2, awning, minimal solo shelter, etc.
*MSR suitably answered my questions via email.
*Not in REI stores. Online only.
*Perhaps a few dollars more than some comparable cottage goods.
*Emergency packaging/soda can size. Good communication for mass market, but readers of BPL will unpack and test before bringing on the trail.
Note: The factory packed, PU-coated nylon taffeta, soda can sized stuffsack shares it's bottom panel with a larger silnylon stuffsack inside. Easy to re-pack in the larger sack, if less elegant. This is only a small price to pay to see such a product carried by a major retailer.
Edit: Downgraded from 4 to 3. I just returned it to REI after a whole year (so I guess you can add a point to REI) because it is just not big enough to inspire confidence. I haven't found a bivy I like, so I never use the E-Wing.