Should you put your Sitecore site behind a load balancing proxy you will run into a bit of a problem with analytics where all the Engagement Analytics app would ever report would be your own load balancing proxy’s IP address. Needless to say that is fairly big loss as you are unable to reap a host of benefits of the Sitecore CEP like page personalization, automation and reporting.
While our website was running on Sitecore 6.4 this problem was already solved and we have implemented something akin to the solution from Jeroen’s blog. Meanwhile Sitecore has reimplemented its analytics engine from the grounds up in version 6.5, and I should say they did a great job on that. However in the process the API for the analytics has changed to a degree that made our current solution obsolete, basically what we got logged looked as follows: