I own quite a few rifles with Sako or M-16 style extractors, and as stated, they are typically superior to the M700 extractor, both the old riveted ones and the newer spring material insert ones.
One thing you should be aware of, however, is that machine cutting the bolt face for the Sako-type/M16- type extractor to fit in a M700 bolt, you have pretty much defeated the action designed gas deflection characteristics of the M700 action by doing so.
Just something to consider when having it done as it will affect how hot gases come back through the bolt in case of a cartridge case failure. Failures have shown that instead of containing the hot gases to be expelled through the action ports and through the bolt itself and into the magazine as the M700 design dictates, a lot of hot gas comes directly back through the extractor cut at the shooter's face. The pressure will blow the extractor to parts unknown and the machined cut becomes a pathway for hot gases to blow out of the action.
I'm not saying don't do it. Just be aware of the effect it has on the overall safety design characteristics of the M700 action when you do it.
Of the two styles, I would recommend the pinned M16-style of extractor over the Sako style as it "might" handle the pressure a bit better being pinned in place before it goes into orbit.