Now that we have multi-morph and a decent IK built in (according to the pre-release stuff at least), it makes sense to rig in Carrara. Poser is a nice cheap purpose-built software. I would never go to it for rendering or modelling, but it does do the one thing pretty well. I recall exporting several things I did in Ray Dream because it was just simpler and cleaner to rig and pose them in Poser and use the output from there. These days I'm on the make-stuff-for-the-poser-users bandwagon so I haven't given the rigging within Carrara much thought. I've used boning as a way to customize shapes and generate morph targets, though.