load balancing 2 shibboleth IdP servers

[Joseph Fischetti]

>NetScalers of various flavors over the years. We have active/passive between two sites via GSLB with 2 servers actively live at the active site and 1 at the standby site. DNS only points to one site at a time.
     
Similar setup here, though we're active/passive on primary site (and passive on the secondary site). We're set up that way for HA not load (so maybe not answering your question)... 
Load hasn't been an issue since we're only handling a few hundred k logins/month (Not counting SSO).  I.e. last month it was around 400k user/pass hits against ldap from shib.  2-3x that for the number of SSO hits.