Hi Burrman
I also use Carrara and have also wondered how it compares to other packages. I'm new to the 3d world and its a hobby so have no great wisdom. I have found the book 'Digital Lighting and Rendering' a useful read as it explains broadly what its possible and how to achieve good results. Its also a book you can read away from the PC which I rather like. It might be particularly useful to you as it explains how to speed up your work by avoiding the use of GI and other time consuming methods of rendering.

If you do find a magic renderer please let me know.
Keith