We blanked the EGR completely on our 2.4 jtdm 159 more than a year ago and the car is much better for it. We just ignore the warning that comes up for a few seconds when you first start the engine. The turbo definitely spools up quicker because it is getting all of the exhaust gas it needs without some of it being routed into the EGR and buggering up the inlet system. We have just completed a 2,000km road trip from Adelaide, South Australia to Brisbane, Queensland and the car has been running superbly. I am sure the fuel economy is improved as well. It has returned 36.5 and 34.8 mpg so far, using brim to brim calculations which is the only way to get an accurate reading. As Fixitsan says, this is very bad technology and needs to be completely eliminated from our lovely engines. I'm buggered if I am going to allow something that does nothing for pollution to destroy my engine. There are no downsides whatsoever to completely blanking it.
2004 GT 3.2 V6, Grigio Stromboli
2008 159 ti 2.4 JTDM Sportwagon, Grigio Stromboli
1989 75 3 litre V6, black
1988 75 3 litre, red, (son's car now)
2000 156 TS 2 litre, Cosmos Blue, (daughter's car)