Using an F5 server as reverse proxy cache (instead of Varnish) Does anyone have any experience, positive or negative, with using Drupal behind F5?

Did you succeed or fail? 

In either cases, what functionality did you achieve? How far did you get?
I have used F5 as a load balancer with Drupal without issue. We were using varnish between Drupal and the F5 as a reverse proxy. 

Pressflow and varnish have been tested well together, F5 is quite a high end bit of kit so I don't know if anyone else has tried it. From what I remember F5 is very flexible so you should be able to get it to work in the same way as varnish (same headers being sent etc).