I have all versions of Poser (from 4 through Pro) and I am a great fan of it.

BUT

I have also had Carrara since version 5 (I am presently installing the 7.1 update.)

Honestly, though, Carrara has been a long haul for me.  It requires a lot of relearning and I have not had the time to sit down and learn it like I did with Poser.

That said, I have been doing a lot of render tests lately and here is what I have concluded.

The latest version of Carrara is hands down faster then Poser (Pro of 7).

It is not 64bit and will not access more then 2GB of memory (where as Poser Pro will during render).

This does not matter, though as it (Carrara) is a much more efficient render engine. (I have not pressed limits, though, I might sing a different tune with something like 5 V4s loaded or something liek that).

To master Poser you have to do a lot of "faking".  To truely get great results in an image with Poser you have to learn a lot of little tricks with lighting and the material room.

With Carrara you just have to learn how to use the materials.

(For example, there is still no consensus on the perfect skin texture in Poser... Subsurface scattering is a fake process with varied results.)

Carrara has true subsurface scattering, true caustics (much improved in 7.1) and it does true GI.

Can it produce a better picture?  Well, that can only in the end be determined by the artist.  There are many fine artists who use only Poser (or Daz Studio, for that matter).

What makes Carrara really worth learning is the little extras that it has over Poser.  The ability to turn any object into a light source (new with 7.1 from my understanding), the ability to generate particle effects (though there are some nice products for Poser that allow similiar ability), the ability to generate landscapes (rivalling or even better then Bryce).

What Carrara lacks (from my understanding) is dynamic cloth (though with Transposer and Poser 6 - not Poser 7, sorry - you can import a Poser scene with Dynamic Cloth).

Poser is still much easier to learn and use in the Poser Room, but the true poser of Poser comes in it's Material Room, which requires a lot or reading, experimentation and practice.  For a totally new user, Carrara's Material set ups might be easier... though I'm just starting to wrap my head aroudn them, so I don't know.

Does this help anyone, or am I just babbling?  It's been a long day...