when I think of building bikes, not only do I think about what the bike is going to be like, as in its ride characteristics; but I also take into consideration things like what is available, what things cost, what the resale chances are, etc...

its seems to me that the Salsa Casseroll compared to the Soma DC, is... dare I say... more unique. In that I mean... things like perhaps how "popular" each one is.
I know around here, CX bikes are very popular, not only for of course racing CX, but also Fixie "kids" like them too...

unless of course, you really like the Casseroll (maybe its the color, or something) then thats that.

the thing with bikes, is that the only way you are going to know what you like, is only by actually going thru the reiterations of a million little variables.
which then comes to... one day... you may seek out a custom bike...