I'd buy it, but maybe there should be a limit on how many you can buy. It also really depends on what the drop rate for them ends up being (like, if it's terrible, which I doubt... yeah Xur should sell 'em. But if they're pouring out of your ears, nah. Like, if you can get 8-12 of them for doing a Nightfall, like ascendant shards, nah, because then they're easy enough to get).