Performance Bench Marks

I have recently stumbled upon JXTA and have been trying to find performance numbers to backup some implied assumptions about the technology that I have derived from the JXTA books and white papers.

1) The number of members in a peer group is not limited.
2) The performance of a peer group is based on the connection speed of the peer's communicating with one another and current network traffic.
3) Is it conceivable to have a peer group with 1 million members exchanging 250-500k data files?
4) Once a peer group is established, the peers and rendezvous peers handle the load, the peer group is not dependant on a central server?

Any experience and/or insight into these performance related items would be appreciated.

-Ken