We are looking at the same options.
Webmail Pros:
- Less support
- 1 password, instead of syncing your ID file and such, can be a pain for users.
- Only have to support a web browser, makes it easy for upgrades.
Webmail Cons:
- The sametime client in webmail does not currently support Audio/Video
- There isn't any sidebar widgets for Connections.
We will probably split our users up into 2 categories. "Power Users" and "Basic Users". The Basic users will get webmail and Power Users will still use a rich client.