As far as i know, this will be no Problem because you can run ezPublish in cluster mode: http://ez.no/doc/ez_publish/technical_manual/4_0/features/clustering
So the limitation is on your hardware. more servers = more pages u can serve/month
Those pages shows ho to setup a ez cluster usign database for everything (caches, media files...), but this will increase the database load. It's also possible to use a NAS for this.
I think it should be good to add some doc at the ez website, for setting a cluster in the other way. (using NAS or something)
If money is not a issue then I would recommend a SAN setup, scales a lot better then NAS because eZ Publish uses the files system quite heavy(4.1 will improve the situation a bit, but SAN is still superior to NAS).
I have seen numbers from 80- 140 (local disk) 120 - 180 (SAN) req/second pr server, so this should be possible. But since a webpage contains more then just the html (images, javascript, css, video), you should use a reverse proxy like Varnish in front independent on how you choos to setup eZ Publish to lighten the load on the backend server(s) and be able to have a decent headroom to scale on.
Another important aspect is how the traffic is distributed during the month / day. You need to plan to have capacity for the peaks, not the average. If 250.000.000 is the average per month (about 96 req/sec) you could have twice or even three times the amount of traffic during day time, but this depends on the type of site you have.
