Another vote for if it isn't broke, don't fix it.
I have to back George as well.
When I worked warranty for Rem. The biggest and almost only repair done on 700's was the extractor.
Usually if they are good ones they will last.
I too install the Sako type extractor, but mainly do it on custom rifles, or only if the original is bad.
As for the bad reports on Sako styles, I would have to say they where not installed correctly. I have yet to see a properly installed one fail.
As for safety of them, I once intentionally kept loading hotter and hotter untill I got a case seperation in a rifle that I installed one in.
There was no sign of the extractor comming out along side of flying out at someone.
One done right will be next to impossible to fly out as when the bolt is in battery, it is partially blocked from this by the lug action.
Celt