I like cats, but, I will never have one in my home along with my Epson.
I used to have two cats. Used to be a bit of an audiophile. One time I opened up a my tube pre amp, and was stunned at the amount of hair that made it inside that thing. That stuff gets everywhere. Don't miss it.
Now, as far as dust, it seems that the P800 is pretty well protected when closed up. My place is pretty dust free, because it's a nicely sealed two bedroom condo with central air. But, I'll get a cover if some here feel it's necessary. Better safe than sorry.