We use it with 10 accesspoints and ca. 100 users. Works ok with a mix of mac, xp and vista clients. No problems at all. The first vista clients was set up with SecureW2, but after beta6 came out we used peap.
By the way – the mac clients only need the CA-cert to be installed on a keyring – click on the wireless symbol – put in the username and password – and it connects. No need for any configuration.