I went from Carrara 1.1 to the toolkit last year and have never regretted it. The phong renderer is very fast, which is real handy when rendering light and material tests. I still use Carrara for some file conversions and to increase polygon mesh resolutions (EI modeler uses nurbs not polygons). I upgraded to the full version of EIU because of raytracing and the plugins available. Be prepared to spend some cash on plugs because there are some great plugins available (check the EIU website for links). I just picked up the psunami plugin from the Northernlights December sale. Great water plugin.

The toolkit should get you up to speed pretty quick and is definitely worth buying. There is also a great book which was just released "Professional 3D with EIU" by Lance Evans.

Hope this gives you a little more insight.

Tim