If you don't animate or use dynamic cloth and hair the native Poser importer is fine in Carrara without transposer.  If you have a copy of Poser 5 or 6 you can still get transposer to work.  Of course you can set up your animations in Carrara as well.

Carrara is capable of creating landscapes that almost rival Vue, the plants aren't as realistic, but are fine for distance shots  Carrara's new replication command can mimic Vue's ecosystems if done properly.  Carrara also works better on systems with slower processors and less ram memory than Vue does.  A lot of people are having issues with Poser imports on Vue 6, if doesn't take much to have Vue crash because it uses up all the system memory.