3rd overall gets you a player like Forsberg, except a year behind in development. Likely a junior as opposed to someone who gets it done in a higher end league. 1st or 2nd, I'd say go for it. 3rd has a slight drop off associated with it.
Klefbom is a top 4 DMan in all likelihood. Probably nothing more, but it's possible. Most 2nd round picks won't turn out to be top 4 defensemen.
If you have Forsberg, keep him. Although I don't know the parameters of your sim league, so maybe Forsberg and Klefbom are a little worse than I think.