I think part of it could be atributed to last minute jitters.
The reasons we are all discussing :
-she is not physically mature
-she loves her International Studies teacher and skipping now would mean only few more months with her, as 7th grade does not have IS. She learns tons in that class, knowledge usually not offered in US schools at this level.
-she fears she will loose her edge in academic competitions, and we do a lot of those.
-both 5th and 6th grade science are very hands on and she is beginning to get really into it. She loves hands on aspect of that class.

As for trying it for a few weeks, well, she is already taking 2 classes a day with 6th graders (LA and Math), they are also mixed for Spanish. My understanding is she will continue to be accelerated, but will know more tomorrow:-)