Hello, I am Jamie Robe, author of the Plone 3 is clearly the path to the future of CMS
However, it pays to think through conversions to new versions of anything, especially when it comes to something as complicated as an advanced CMS.
Plone is currently supporting two "families" of the software - the 2.5.X and the 3.0.X.
It is important to consider your site content types and how your site is constructed, before embarking on an upgrade (migration).
Are your third party Plone Products also upgraded to support the new version of Plone?
This is one of the toughest problems when facing any migration. For instance, you may have used a product to store and display 1000's of photographs on your site. If that product hasn't been reprogrammed by its creators to work with the new version of Plone, you may find that all your photos are "lost". They will not really be lost, but they will most likely not be viewable on your site. It is always best to use Products that many others are also using, that seem to have a team working on them all the time.
How much time are you willing to put into any site upgrades?
Even if all your Products have been upgraded also, it can be time consuming to migrate your site. It is usually pretty easy to do the basic steps, as long as nothing goes wrong! That leads me to my most important point - NEVER EVER EVER EVER try to migrate your live production site(s) to a newer version, while they are your one and only live site(s). If you don't use a test install of Plone to do this work - and TEST TEST TEST everything, you have a good chance of pulling the rug out from under yourself.
Are you willing to learn the new features and adjust your site to take advantage of these?
Upgrading is good, especially in terms of keeping up with the latest security patches, etc. However, going to the latest version may not make sense unless you are willing to learn hwo to use the new system correctly. While some of the older methods will carryover, jumping to Plone 3 means a change to some of the fundemental ways of building a Plone website.
I am not trying to scare anyone off of Plone 3. I myself am moving that way. If you are working on new sites, consider starting with Plone 3. Run both in parallel. Install Plone 3 on your PC at work or home and test it out. Remember that this is never ending, and as soon as you get Plone 3 figured out, Plone 4 will come out :-)
