I've just finished testing Endnote 7 under Crossover Office 3.0. My impressions are "much better" than under 2.1. Specifically, as mentioned below, the "no checkboxes" issue is fixed, allowing selection of output styles from the style manager, and the window flickering is better, but when editing an individual reference, it still uses 100% CPU. Not a showstopper, just slightly annoying. It's the only thing stopping me from giving it a gold.
Integration with Word appears to work well, and the RTF document scan feature, which allows you to copy & paste references from the Endnote window to OpenOffice.org, Kword, etc, and then later run the resulting RTF file through Endnote, letting it put in proper references & build the bibliography also works well.
I've posted one issue to "Tips & Tricks" as well.
Edit: The system is an up-to-date Gentoo system, with XFree4.3.0, Nvidia binary drivers, and a custom 2.6.6 kernel