I just bought P4 and Pro Pack from Daz a few weeks ago and feel 'safe' about getting caught close to an upgrade. The Pro Pack FX book that came with touted this as what could have been P5 but Curious decided to make it an add on to P4 instead. That's a good thing. So far, I'm really happy with it (after running the patch). I remember getting all lathered up when Bryce 5 was in the works and eventually bought the upgrade. I could have stayed in B4 a bit longer skill wise, though I don't regret buying the upgrade. Lots to learn and having the new kid on the block is not always necessary until you're ready for it. Heck, I'm still using freeware modelers. That's my 2 cents.