I have Vue 5 Esprit and Carrara 5 Pro. From my opinion most have been said already. For Architectural Visualizations you shouldn't need Infinite. If you need a better or more detailed vegetation, just use your money for Xfrog. These plants are certainly superior to the ones from Infinite. There isn't really much you can't do with Carrara compared to Vue. Some things maybe in a different way. For your purpose Carrara should really be enough. It's more worth to put the money maybe into some plugins for Carrara.