IBM Cognos TM1 Performance Modeler and Architect: Potential Collaboration Pitfalls (Link from from Ironside group)
IBM is encouraging developers to use Performance Modeler as the main tool for creating and maintaining TM1 server objects. Performance Modeler offers many features that Architect simply does not provide. The push toward Performance Modeler is evident in IBM’s documentation, presentations, and rapid update releases for the tool. For now, Architect will still exist and will continue to serve as a development tool. As future releases of Performance Modeler provide more and more functionality, Architect will likely only be used to maintain older TM1 versions going forward.
However if you only want the bottom line:
The easiest way to avoid most or all of the issues listed in this document is to choose Performance Modeler or Architect and stick with that tool through the development and future maintenance. Most of the contention issues between tools occur when the initial object development is done in Performance Modeler and then opened or modified within Architect.
Conversely, there are very few issues when the objects are initially created in Architect and then modified or managed within Performance Modeler. For this reason, if using both tools in an integrated approach, developers should try to move work from Architect to Performance Modeler and not vice versa.
And a TM1 Performance Modeler and Architect Comparison- Webinar (also by Ironside )