There's only one other cat I've seen in our neighbourhood and she runs away at the sight of anything, human or animal, so not really the best way to judge, but they got on ok with Casper when they were at my mums, even though he used to chase them!
We have too much stuff for a flat (garage is stuffed with car bits) so that's unlikely, although we don't have a cat flap where we are, so the cats can only go out when there's someone home to let them in and out, which is definitely a consideration.
I did ask her current owner about other cats and she said that she used to live with another 2 cats and got on fine with them, although that's obviously no guarantee. I had also thought about asking my Mum about her as she misses cuddles with my 2 (casper isn't a cuddle sort of cat) but she's currently looking after a friends cat for a month so wouldn't be able to even consider it for a while.