I have both the Gen 1 and Gen 2 Magwedge rails. The only "issue" I've had with them isn't really an issue with the rails, so much as with the SKS.
SKS's were built to fairly wide tolerances, so it took a slight bit of tweaking to get them to fit properly. But that isn't the rail's fault, it's the fact that, well, there's a lot of variance in production SKS's.
Once tweaked for fitting, the Magwedge rail is solid and holds zero very well. It even returns to zero almost perfectly after flipping it up for cleaning, and then re-affixing the pin.
The angled underside of the MW rail does a good job of casting the spent brass to the side. If anything, ejection is
more predictable with the rail in place than without. I've had zero issues with stovepipes since installing, and on one of my SKS's I used to get stovepipes on a semi-regular basis.
I can't comment on the Wartak rail -don't own one, so won't make any claims to knowledge about how they work.
All I can say is that I'm very happy with the MagWedge. Any of the complaints I've seen, strike me as a case of "someone doesn't understand basic mechanics, and probably should call a friend to install things on milsurps" type issues.
After I finished accurizing the action, and took of the bayo, I was getting about 2&1/2" groups out of that rig, and it filled the freezer with venison this fall. I think the only way I could get groups any tighter out of that rifle would be to go with a fitted Boyd's stock (screw CrapCo), and I'm seriously contemplating going down that road.