If your group demands Izanagi's find a new group that knows what they're talking about. If you can aim Whisper will outdmg Izanagi's in most fights over time. And there are plenty other setups that work just as well or better. Hell, almost any high impact sniper with triple tap and possibly even mulligan will be nearly as good. I'd almost be willing to wager that even Polaris Lance will do viable dps simply because you never have to reload if you can hit the mark reliably.
Bottom line ..... avoid raid groups that demand their members to have certain items. There is always an alternative. If 1k wasn't so rare ppl would demand that over Izanagi's but kids can't demand something they don't even have themself, can they ? So don't let groups like that mess with you. Just move on and find a more mature group that is less focused on youtube/twitch item hype and propaganda.