I purchased P4 Pro Pack some 2 years back, and upgraded immidiately when P5 came out. My eperience is that P5 seems to be a bit slower to work with (a tad slower on responsetime) than P4 PP did. I haven't installed SR 3 yet, though, and that should supposedly optimize the speed of P5. I really dig the materialroom of P5, I have yet to learn the cloth room (though it does seem to have some potential). The faceroom only works with the P5 characters (and they are not quite up to the V3 standard, though they are useful characters even if they do need hard work). The hairroom does not produce good results as far as I'm concerned (if somebody disagrees with this, please point me to a good P5 Dynamic Hairpiece that is convincing without slaying the machine). The Firefly rendering engine is better than the crappy P4 engine. I'm not sure what the current prices are, and how much cheaper P4 PP is over P5, but if the price is no issue to you, I would recommend that you go with P5. I still have P4 PP installed, but haven't run it once since I installed P5. Regardless what other people think (and there are huge disagreements over P5), I've been quite happy with it. But then again, regardless which version you'll end up purchasing, I promise you this: You'll be very glad you made the buy, Poser will steal what sparetime you have! :) -Hanz