The only problem I can foresee is the multiple installation of model in various runtimes.  That might cause conflicts when injecting morph characters.  Poser does conduct a search for necessary files and will load the first files it finds whether they are right, wrong or corrupted.  The updaters might also get confused.  If you still have older Poser versions available on your computer, it would be wiser to link your runtimes to a you current application and not reinstall any models unless you intend to totally uninstall previous installs and their runtimes.