[Zope] CMF/Zope scalability

[Tom Cameron]

I have a client who is interested in using the CMF to build a very large
system.

I am wondering where I could find some proven metrics on its limitations. In
particular, how many members could be handled using the standard Zope
acl_users methods.

I am not worried so much about load capacity, that can be tested using
common techniques. But I am not certain about the ZODBs ability to store
large numbers of objects and the Catalog to handle searches over these
objects.

Do you know of any sites/research where I may find some answers?

Naturally I understand that this depends on many other factors, but can
anyone provide me with actual experiences?

Thanks
Tom