One of my coworkers has the ENO ember underquilt, which I believe is the one you're referring to.
Couple of issues he had with it...
-By design, it wraps tightly around you, decreasing efficiency by compressing and not allowing insulation to loft
-Elastic bands make fit snug around his doublenest, making it tough to diagonal hang
-Condensation was a problem in South Carolina sub 30degrees
Hope this helps