I'm wondering if there is any distinct advantages to grouping your meshes while they are still in the modeler app over grouping in Poser's Set-up room. I tend to like the idea of letting Poser do it automatically then I can simply go in and refine it.

Basically, I find it tedious to do grouping in Poser. Sure, it can do it automagically, but that's not often the best way to group every item. For instance, I may have constructed geometry purposefully so it can be grouped a certain way and so that deformations occur as I want them to. That means that many groupings will end up being done by hand, by myself, rather than relying on Poser's Setup or Grouping options.

I find, for instance, Autogroup Editor, sold here, to be easier and quicker to use than Poser, simply because it's UI, camera and manipulator is more standard 3D modeling fair than Poser.

Are there any advantages to grouping outside Poser? Well, I think all the posters, so far, are correct - It's up to the user and their comfort with and knowledge of the tools they're using and what they find most efficient and desirable. A group is a group is a group, as far as Poser is concerned, and you can select certain faces, individually, in Poser's grouping process, so there's no real technical advantage to using outside programs.