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Chicxulub: Not an impact structure?

I don't think I've ever disagreed with Frank on any post to the list -- because he is almost always right on on everything.  But, I must play the Devil's Advocate on his Chixulub post (which I believe now has been conclusively proven to be an impact crater).  

Here are bits of evidence which are compelling:

A global layer at the Maastrichtian-Danian boundary with a large, but variable, enrichment in iridium (by neutron activation analysis).
Global occurance of charcoal from burned vegetation in the same layer (from Gubio, Italy to regions in North America and so on).
Shocked quartz in the smectite clay layer that are only known to occur in nuclear explosions (bomb test site craters) and in impact craters. Dated to +/- 10,000 to 100,000 years of the K/T Boundary by various scientists.
Potassium feldspar grains shocked and melted to glass spheres and distributed spatially in greater population closest to the crater site.  Dated 64.98 million years +/- 50,000 years ago.
Yellow glassy tektites in bedrock formation on Haiti, other Carribean islands and Gulf Coast that are classic crater ejecta.  The richness in Ca-S match the Ca-S rich target rocks near Chixulub.  Absolute age of tektites: 65.03 +/- 0.1 Ma.
Tsunami deposits throughout the Gulf Coast at the K/T Boundary layer (such as Brazos River, Texas).
The event in the K/T Boundary layer is only 1 cm thick indicating a very small duration...possibly 1-2 years of global burning and "nuclear winter" types clouds.  Short enough that some trees survived, but long enough that others did not.
Mass extinction on a global scale precisely at the K/T boundary.
PEMEX oil company drill cores showing shocked materials at the Chixulub crater site and mapping showing crater deformation.
Tomography imaging (from satellites using magnetic and gravity anomoly sensors) that clearly shows an impact crater at Chixulub.
A probable piece of the impactor recently found in an ocean core sample that dates precisisely to the K/T Boundary.  Definitely a meteorite fragment, definitely the right age. 
The Chixulub formation was mis-identified early on (1952) as a volcanic site by PEMEX.  They thought they were drilling in old sediments and then discovered what appeared to be an andesitic volcanic structure underneath.  Studies since 1991, have conclusively shown that these rocks are not volcanic adesite, but are impact melts almost identical to nuclear test site melts in sedimentary rock.

These are not the findings of only one scientist.  There have been numerous papers on each of these individual pieces of evidence, adding up to more than 200 scientists who have contributed field work and lab work to re-create the K/T impact event. The only hold-outs to date have been some dinosaur paleontologists who have pet theories for the K/T extinction event (i.e., Bob Baaker puts forth a global disease epidemic spread across land bridges between continents -- but offers no evidence).

However, I thank Frank for his post because it got me to mulling over all of the evidence from a multitude of papers I've read since 1991 -- and reaffirmed my confidence in the scientific work done since Alan Hildebrand and Glen Penfield published the first Chixulub paper in Geology, in September, 1991.  (And credit should also go to Luis and Walter Alvarez suspected that a giant impactor may have triggered the K/T extinction and put forth the theory in the early 1980s even though they did not know of Chixulub.

Steve