I'd like to address it as early as possible. His health concerns me some, but I would like him to stay. I would think a good argument can be made for him getting a bit more than G and, at the same time, maybe a good argument can be made for him getting less. I would love for him to get an identical deal to G, and think it would be very fair, but I think he'll end up getting a bit more. For arguments sake, however, I believe G averages more points, plays more minutes, has an all star selection, is viewed league wide as better defensively, has received more Norris votes, has significantly better health and durability and arguably is more important as a first pairing RHD. I don't know if they'll be able to build that case in order to get Staal for less, or an identical deal, so I'm assuming he'll get a bit more.
With all of that said, I'd like to see 5/6 years at 5.8M. I'm fine with 6M, if that's what it takes. I don't believe he should get more than that, especially with his health record. If his initial demands are above that and we cannot get him to come down to 6, we should look at dealing him as early as possible (which means we need to get on the extension process as early as allowed as well) so that we're not simply moving him at the deadline under pressure to "get something" for him. If push comes to shove and his demands are unreasonable he can be a very valuable trade chip, especially if he remains healthy for the rest of the season and some playoff games and has a strong finish to the season/playoff performance. I would much rather get him locked up long term, but if we can assess his demands and figure out where we are early enough, the best time to deal him if there's a sense that his demands are out of whack or he is intent on testing UFA/joining his brothers would be before the season begins or extremely early on so that the team picking him up is getting a full year and not just a potential rental.
Much prefer to keep him. Mostly depends on his intentions and contract demands. Anything 6M or under is good. An identical deal to Girardi is perfect, and I think a very good case can be made in negotiations, based on all of the factors I first mentioned, that he shouldn't get any more than that.