First off, bring up [i]all[/i] exotics. There is no reason not to. Sure, some are op, but just nerf them a little. Don't throw them out and screw over those that worked hard for them. And when you do bring them up, don't reset all our upgrades. That's just stupid! Why would you do that?
Now for legendaries. I get that you want us to move on and use new weapons. But there's a way to both push us towards new weapons and let us continue using old ones if we really want to. Have new weapons start with higher attack values, but let us ascend old ones. But make ascension a grind. Make it easier to simply get a new weapon than ascend an old one. That way, people will likely use new gear, but if they're [i]really [/i]dedicated to those old, signature weapons, they can still use them.