I did the delete on my 300zx (Kind of off subject but still an EGR) car runs about the same......no real performance increases that I can tell. From all the reading I did on my car I understood that the egr works all the way up to 2-2500 rpms then it closes and no longer circulates gases. So I would assume that in theory if one were to delete the egr it would increase the oxygen input and cut out the recirculated gases from the exhaust and give you a stronger pull on idle and in the lower rpm range.....I plan on trying to figure out how to do this on my yukon a little while down the road. I think it could make a difference in mpg since my rpms normally run at around 1800 at 55mph if my memory serves me correct. (but this could just be wishful thinking). If anything I think it is a good thing to delete if one can do it properly....in my eyes it is just one more thing that can go wrong.....
Also....from reading about the 300zx I learned from owners that the EGR likes to get clogged and stick wide open causing the motor to constantly draw gases throughout the entire rpm range....don't see a real engine damaging issue, but I can def see a little performance being robbed if this were to happen.