I would lean toward the Export Wizard. Run from Management Console, you can then follow the prompts to select the dependent objects (in 9.2), ensuring that none of the linkages are broken during migration. Also, this allows you to choose a specific part of the content.
For metadata elements, this is addressed within the wizard. However for SAS code (such as code nodes in DI studio or Stored Processes), you will need to estabilish macros/processes to ensure no code modification is required when moving from one environment to the next.
There are many strategies (user papers, etc out there) that provide ideas on how to accomplish this. A simple technique that I recommend is estabilishing a set of your own 'reserved macro variables' in the autoexec_usermods.sas file (on each system Dev-Test-Prod) that are then used through out the BI infrastructure.
There isn't a clean mechanism to promote SAS Portal content. It is typically much easier/cheaper to create content in the Portal than it is to attempt a metadata move.
Suggest creating multiple groups within the Portal (in Production) and assigning a content manager from the business to create the content for a 'test group'.
Example - two groups would exist for each content area. An 'Executive' group where all the executives are members and you are the content administrator, and an 'Executive Development' group where the business content creator can develop but none of the actual executives are a part of/can see. As the web administrator, you have the ultimate ability to reassign the content from the 'dev' group to the live area.