Hi All,
Just saw the comments about flying blind :)
Frankly, we are greatly impressed with the design quality and could happily choose any of the first 10-20 designs. We are ignoring small preferences like color, as we recognize this can easily be easily modified after the winning design is selected :)
In terms of fonts, we have gravitated to a clean, classic look (See the top 12 or so ranked designs for examples), we feel that caps or lowercase works equally well (From the ranking of both CAPs/No caps, we obviously can't decide) :)
Our small group does like the more graphical "x" of some of the designs, although we feel its important that it is still recognizable a a letter in its own right.
Based on our discussions (and review of the current submissions), we are looking for a simple graphic that has a unique impact. We feel that many of the variants on "Dx" fit this bill nicely. We also like #44, for its clear and direct presence :)