Who require RRC thick Client to be installed on their desktops ?
Developer Require ? RRC WebClient / Thick Client
Project Manager ?
Test Lead ?
Business Analyst ?

The web client in RRC 2.0 is for review (read-only), team-based commenting, and participating in review and approval workflows.

The rich client is needed by anyone who will be creating or editing documents, creating collections or reviews.

Which people are these? It depends how your teams will use RRC. The RRC product team allows a wide group of people to be authors. Product Managers create requirements and various background documents. Developers create design documents and capture notes from their daily stand-up meetings. Testers do some thinking/planning as part of creating test plans (and create documents in RRC to capture that. But mostly testers are readers of information in RRC, which is a "one stop shop" for information that helps them create effective test plans. And the documentation team likewise are mostly readers.

You can read more in these post on jazz.net:

Engage your customers. Introducing Rational Requirements Composer 2.0
http://jazz.net/blog/index.php/2009/11/24/engage-your-customers-rrc-20/

Only 5% are requirements
http://jazz.net/blog/index.php/2009/08/31/only-5-are-requirements/

Drinking our own champagne: Using RRC 1.0 to develop the next version
http://jazz.net/blog/index.php/2009/07/16/rrc-drinking-our-own-champagne/


Daniel