I would add a couple of other Criteria when evaluating a web platform.

1.  What is the depth of documentation available.  No matter how good the vendor may be, there are always holes in a vendor's documentation.  Even Microsoft relies heavily on bloggers and book authors to fill in the holes in their documentation.  Microsoft provides extensive technical documentation on their products, yet I am often forced to turn to third parties to get the information I need.  A quick scan of any of the book sites like Amazon can show you how pervasive a given platform is.  Editors tend not to approve book projects for products with a relatively small number of users.

2.  What is the job market like for the product that you want to base your enterprise around.  If your administrator leaves tomorrow, how hard will it be to replace him/her?  If you need a custom extension written, is there an avenue for you to get the plug-in created for a reasonable price.  Even though the product today may meet your requirements, eventually your requirements will change (probably even before you finish getting the system fully implemented) and you will need a platform that can change with your requirements and for which developers, designers and administrators exist who can help implement the needed changes.

3.  How frequently is the product updated to address bugs or to keep up with the current standards?   I have seen lots of companies that take one or two years between major releases and generally have a couple of patches in between.  Is this likely to keep up with your business?

I will leave it up to you to determine for yourself how the various alternatives stack up.

Tor,

I suggest to create a new thread instead of "hijacking" an existing one, this will also give your request better attention.