Apologies in advance for the "how long is a piece of string" type of question.

It looks like I need to do some planning for deploying Filr in our organization. We are OES shop with ca 800 users (soon to be 1000) so it seems that "small installation" of Filr just might not be sufficient. I'm trying to decide whether I should fit a "minimal large" installation of 4 appliances into our existing virtual infrastructure (assuming they have necessary amount of spare CPU/RAM) or should I deploy each Filr appliance on a separate physical machine. What are others doing in this regard?

And, while I have your ear, is anyone running Filr on Citrix Xenserver?