iRule to work around Windows patching schedule

Would it be acceptable to display a "Please try again later" page to users who have a valid persistence cookie but whose chosen pool member is down?

 

 

I agree with Michael; I think the "action on service down" to "reselect" is probably the best option if you want to avoid annoying your user population with splash screens or "page cannot be displayed". But this application's design is pretty much shoehorning you into a very difficult posture.