I think the ONLY issue I've heard of with factory Sako extraction wasn't the extractor directly but had to do with the angle of ejection. But both extraction and ejection are interrelated in that the case head is held by the extractor until the ejector pops the case out of the action. The issue with the angle of ejection in a Sako was reported in a thread here on AHF by Toby458, IIRC. In that instance the angle of ejection was too high and the ejected case was hitting and rebounding off the scope or scope turret then ending up back in the action causing a jam or potential jam. I wouldn't think that type jam issue to be common, but surely one of the things to check for when setting up a new rifle- no mater the brand. I have not experienced any issue with two Sakos I've owned.
I've had similar instances, not with the Sakos, but with a couple of Winchester 70 CRF rifles and the one Rem push feed with the Sako style extractor. The issue seems more common and logically so with low mounted scopes. So currently all my hunting rifle scopes (my scopes are simple, have two knobs and no odd reticle stadia, etc.) are mounted rotated 90 degrees left. No matter how easy or hard I eject, the cases clear the scope and turret cover.
Here're a couple of pics- A spent case that impacted the turret cover on one of my M70s years ago and pic of how I mount my serious hunting rifle scopes that helps prevent unwanted case impact during ejection. While these impacts were not causing jams for me the potential was real. Another plus is that it opens up the loading/ejection port so it's easier to load in a hurry.
