Nope, 1.6875 is the correct value, we must ensure that the scaleRatio * device width = 320
As i told you yesterday Android is having such a huge problems with webapps because of the approach of assigning 1.5 to a non 1.5 device.
Please read link notes from wikipedia about qhd (the small link arrow near to 1.5):
http://en.wikipedia.org/wiki/List_of_displays_by_pixel_density#HTC
http://www.sencha.com/forum/archive/index.php/t-174098.html?s=2a5a0bd7492eb9ac6cb2adccb5788d5a