Oddly enough I've been one the ones lucky enough to have had no problems. Yes the rendering time is slow, but I'm used to Bryce so .... I'd recomend adding it if you can, but leave p4 on your system. That way you can learn p5, but still have a dependeable (well sorta ..this is Poser after all) program to get work done in. You can link from p5 to the p4 runtime and use all the stuff you have installed without needing duplicate copies. Mind you, p5's nesting dir are almost worth he switch.