My experience has been as follows:
Prior to the 18-033-07 REV. A&B my milage was 25 MPG an since the reflash my milage is 19 MPG . Except for the Overhead Consul warning and the Mil light the truck always behaved as expected no reduction in power or any other bad behaviour.
The poor milage is a direct result of the increased fuel usage for the regen cycle.
As to the comments of having to run for 45 minutes or more to complete a regen cycle, I ran for 9000 Km stopping over night for sleeping and it was continually running in and out of regen, the entire trip. There is a real need to balance the agressive regen cycle and something which gives real fuel economy. In My Opinion as an Owner/Operator, Courier