I would disagree with FA being strictly a colo-build. 2 Falcons provides arguably the best burst DPS in the game, and is amazing in raids. Furthermore, colo gear is currently the top-tier equipment in the game, so every skill you use with colo gear is better than without.
As for differences between FA and AV for pvp purposes, I'd also reccommend Falcons. The AI can be buggy at times, but in Colo I've never found it to be an issue. It'll attack someone, however they are kiteable and can redirect their focus onto a different target if the original target runs too far. AV does have a long cast time, but on occasion you can get away with it among the chaos. Unfortunately, since it takes a while to be able to use AV at all, you may not see yourself even surviving long enough to use it. The same holds true in duels, you may never even be able to use AV in many cases, whereas Falcons are instacast.