I have done exactly this on mine. Diamond Eye 4" with muffler, deleted dpf and shutoff egr. I have not noticed any great increases in mpg, although we are getting into winter fuel and longer idle warmups. I have tracked every tank since I bought the truck in Oct 2011 (81k mi), deleted in Nov 2012 (101k mi). I am trying to see if there is any significant change before I buy some tuning, but have a feeling the tuning will do more for mpg than eliminating regens and exhaust restrictions.
current: 07 LMM ec/sb ltz black & black, DE 4" turbo back, egr deleted, Edge Insight CTS, 213k miles
dead: 06 lbz ec/sb white, killed a honda on its way out