Well there were ik improvements and morph targets added. You might care about sound for that. Also those file supports could be important to you...even transposer for poser import, altho you may want to buy transposer2 for poser 5 support. The transposer w/ c4 is old. The motion blur is also in pro not standard. Hopefully c5 will be out at some point soon. There is a comparison on the site...gotta dig for it.

No need to think outside the box....
    Just make it invisible.