We have upgraded two similar farms (one development and one test). The branding/design is identical and both farms are using Visual Upgrade. The farms have different versions of ContentQueryMain.xsl. The dev farm is using the 2007 version of ContentQueryMain.xsl and the test farm is using the 2010 version of ContentQueryMain.xsl.
The 2010 version of ContentQueryMain.xsl breaks some of the branding. I have "fixed" the problem in our test farm by replacing ContentQueryMain.xsl with the 2007 version.
I did the dev farm upgrade using the database attach method. I did not do the test farm upgrade, it was done as an in-place upgrade.
My question is, which version of ContentQueryMain.xsl should be used if the upgrade is successful and Visual Upgrade is enabled?
I had assumed that the 2007 version would be used while Visual Upgrade is enabled and then, the 2010 version would be used after the UI was upgraded. Now that we are seeing mixed results in our upgrade testing, I'm not sure which is correct.