I've never had any problem saying that everything is a file. I usually emphasize that that means not just the things that are files on Unix. Saying everything is a file server or a file system sounds pedantic yet less precise.
The real problem with trying to summarize Plan 9 with a sentence like that is that you're missing 2/3 of the syllogism. The rest is there is a simple way to share files, and therefore you can share everything. Russ
