Atlassian Crowd experiences?

we (a team of about 150) are considering moving our ALM solution from Bugzilla/CVS to Jira/svn/Confluence/Bamboo/Fisheye. SO has a lot of good info on those, but I would be interested to learn about another tool from Atlassian - a Single Sign On (SSO) Crowd, I am considering adding it to the mix for an LDAP integration with our Novell id's.

has someone had any experience with Crowd?
how does it handle 100/200/500 (after recession, that is) users?
any tips/tricks?
would you choose different, open source SSO solutions?

thanks

EDIT: a year has passed...

We got Crowd and went with ActiveDirectory integration along with internal Crowd directory (for short-term contractors, etc.). So far the solution works just great.

EDIT2: Another year: still going strong (We have 1K users now). Nested groups is a killer feature, thankfully it is working fine after last point release.

EDIT3: mid-2012 - 7.5K users - going strong. with a little automation for onboarding (Confluence pages with Ajaxified forms + a little Crowd plugin)

Solution

We're using Crowd with about 80 users and expect that number to climb into the hundred when we roll it out for client access. Crowd is important to us because it allows us to integrate Jira and Confluence (the Atlassian wiki) with SSO, which is critical.

Crowd works well for us but it does have some quirks. We are using it to draw authentications from Active Directory. There are some things that are a little inelegant. We need to do some more digging to troubleshoot those.

But that aside, Crowd is a big win for us, for these two reasons:

SSO across Atlassian apps
Ability to have our internal users drawn from Active Directory, and add clients directly to Crowd and not bog down AD

We're very happy with all the Atlassian tools.