Strata Design 3D CX 6.x is working well on Snow Leopard (10.6).
One issue has been discovered in Design 3D CX 6.0 - an occasional crash when clicking on the Convert button. This has been resolved in Design 3D CX 6.1. You can download the free 6.1 updater here: http://support.strata.com/index.php?action=news&newsid=9&newslang=en
Also, the Strata 3D Vector plug-in for Strata Design 3D CX 6.x will not work on Snow Leopard unless you install the optional support for PowerPC backward compatibility (Rosetta).