Every Vue upgrade so far has allowed me to use the previous version. This is fortunate, since there has been some consistency in the malfunctions of the latest, greatest builds. Scenes made with a previous version of Vue often won’t translate to the newer version when there are complicated ecosytems and lots of objects.  

I can’t justify spending $400  for something I won’t be using much. My use of the last upgrade cost me about $40 per render. I have yet to see a version of Vue that doesn't crash randomnly, so I've learned not to hope that the latest version will solve my functionality issues (which have followed me through several computer systems.)

By the time I might want to upgrade xstream, it will probably cost as much as a high-end CG animation suite. The pricing is almost there already; Pretty ambitious for a glitchy plug-in, but I guess enough people are paying.

Download my free stuff here: http://www.renderosity.com/homepage.php?page=2&userid=323368