I step into this very carefully as someone who uses both programs.  I have to begin with why I use Poser and some strengths and weaknesses. I have become extremely familiar with how to create credible Poser light and I feel it has the most "painterly" of lighting. Also, I love its approach to animation. Though I am pretty catholic in where I buy, the figures I buy are mainly for characters created by Daz3D.  In a lot of ways, Michael 5 is a great evolutionary step from Michael 4 if only because of the possiblites in scaling, better joints, but also because of the future of Michael 5.  Content will only increase for the Genesis characters, and I think that I don't want to completely fall in a hole of propping up legacy figures.  Being able to move between the two allows me to use my now vast library of Poser products with a current figure rather than a legacy figure.  Even the people who despise Genesis (one should mention that there are two groups: those who just see no point in Genesis and those who resent that there is no Poser-ready Genesis) benefit because the figure is now partially driving the move by both companies to add features to their characters. I get to continue using my favorite vendors (Luthbel, Rawart, etc) without tying their hands in terms of what technologies they want to employ.