Haven't really studied gasoline engines on how EGR be worse or better on oil, but have dealt with EGR equipped diesels since the EPA started that mandate and it is absolutely brutal on engine oil. Of course there is a lot more soot and other issues going on..... but,
If recycling exhaust gasses back into any engine is a good thing, think of it this way... next time you take a dump, then grab a handful and re-eat it and then your next dump should come out cleaner than the first one!! Not exactly the greatest analogy, but should get the point across.
It may reduce Nitrous Oxide, which may or may not be the great climate change culprit, but either way, I find it hard to believe that it is a great thing for the engine and the oil. Does anyone ever wonder why there is no EGR on high performance racing motors or non-road use construction. ag, and marine equipment? Could it be that EGR is not a great thing to do to an engine?