I suppose one of your biggest issues will be with whether or not your portlets use any IBM-specific APIs that are not a part of the Portlet Spec.
The pros are easy:
1. Cost benefit
2. Runs on JBoss instead of Websphere
3. Community and Red Hat support
1. Limited GUI admin tools (could be a pro as well!)
2. You need to learn how the XML configuration files work so you can customize portal for your specific needs
I have used both products, and for a developer GateIn is great. It's easy to install, easy to use and doesn't require a massive server just to run. Once you get past the learning curve for GateIn, it's a solid product. What's nice is that it works out-of-the-box, so you can use it right away and learn the behind-the-scenes details gradually as you work with it.
Thank you for your reply.
We have about 20 portlets. We haven't really done anything out of the oridinary with any of the portlets. Really the only think that might be IBM specific would be the links generated by portal:urlGeneration. Most of it is JSR-168. In your opinion, should I be able to just deploy my portelts into GateIn, and have them work. Mostly?
Any suggestions on where to get a start on the xml config?
Eric - it sounds like you could at least try to deploy your portlets on GateIn. If a few links don't work, that is probably an easy fix!
For starters, I recommend just using the GateIn web interface for creating navigation nodes, pages, and putting portlets on pages. When you're ready to get serious, you are going to want to start with the GateIn Reference Guide:
Sections 3.3 - 3.5 explain how a portal can be configured using XML instead of the web interface. Once you get to that point, you will have more questions but you'll know a lot about GateIn.
Hope that helps!