3 of coin works good to me. It's all I buy from Xur anymore. Well that and the occasional heavy ammo. I stock up on 3 of coin. I prefer to have the chance of getting 290-310 exotics versus Xurs 280 gear. Through iron banner I've gotten a lot of exotics. 1 per character in a day. Even got 4 in one day and they were all 310. I don't rely on 3 of coin. I turn it on when I remember. Which makes it randomly used automatically. I just feel I get a lot of exotics which in turn gives me shards when I need to infuse.