Personally I think that is a good idea. I don't know if you have downloaded all the additional content you get when you buy poser 11 yet but you will see it falls into several categories, there are the hivewire figures, Dawn Dusk and baby Luna. I keep all of these in one runtime because Dawn and Dusk can share some assets such as textures for clothing and hair, and even some figure textures. (There are freebies for various alien types you can find). I also have a separate runtime for LaFemme and you might decide for example to include the 3d scenery into a single runtime.

I haven't checked them all but it seems the zip files have been updated so they will now work with the "install from zip archive" function in the file menu, so once you add your extra runtimes, you can just use this. It will open a window for you to select the zip file and then you can use the drop down menu in the pop up to choose which runtime you want to add the content to.

Hope this helps