Whilst i can see the enviromentalists theory for leaving the EGR valve in place, try disconnecting it and see how your car runs.
I have disconnected the one on my wifes TD4 for the last 12 months and it has ran much better with it blocked off than connected, even she noticed the car 'Felt' better after i had done it and she is one of them women who puts the key in and expects it to start.
The car even ran lower emmissions on its MOT with it disconnected

it also passed with it un-blocked but with a higher reading but in my case it stays blocked off.
Zippy