If you delete the EGR you will no longer have exhaust gases recirculating to warm the motor, if it isn't at operating temperature, or takes longer to get there, you'll get worse fuel economy and increase engine wear. This is why a dynamic EGR tune was developed, the eco tune is also designed as a $50 add on for someone looking to do deletes, it isn't more economical than any other file. Pump timing is vital for optimal running conditions. I personally picked up about 15 miles/tank on my PD deleting the EGR, it rarely drops below freezing here but I'm still considering reinstalling and running it dynamically just for the sake of better warm up times and emissions.