Go for P6, it's pretty stable (for me at least) so far, it's better than 5, better interface, better rendering options, more flexibility in the material room. I have uninstalled 5. The included content, figure wise, is better. Going from P4-PP to P6 the material room is going to be your biggest learning curve, but well worth it, some MAT files will not apply correctly you will need to tweak them .There are a lot of options for rendering and lighting that were not present in PP. The dynamic cloth room is improved in P6 IMHO. Going from PP to P5-6 will cause you a few headaches when it comes to conforming clothes with joint controlled morphs not always kicking in. There are several workarounds for this. There is no point in buying 5 IMHO.

Dominique Digital Cats Media