[eluser]skunkbad[/eluser]
Yes, I would have to resort to hardware or sticky sessions with mod_proxy. I still prefer $_SESSION.
I think the primary reason why I prefer $_SESSION is the availability of the $_SESSION data, which is different than cookie data (which is what CI sessions are). There are times when I need to get session data for use in a script, but if it is in the cookie it is not available. You might say something similar about $_SESSION, and there's always some way to handle the situation, but for me $_SESSION usage is too easy.