We have actually had a few impromptu games of OpenArena before in fact for a bit I was running a dedicated server from here.
But ultimately it's a different sort of game to ET:QW. Openarena is just about shooting people which I tend to get bored of after a bit. QuakeWars has a good element of teamplay and objective building which I feel could develop into more fun within the group.
Also OpenArena, as fun as it is, is just aesthetically ugly I didn't put a 8800GT in this machine to push around maps like that :)
I also tried Alien Arena but just couldn't get on with the gameplay.