I use to work for the IT supplier whose technology underpinned the DII(C) core nodes and from my side of the fence the roll-out seemed to go relatively smoothly.
Unfortunately we worked with the wrong Prime Bidder for DII(F).
I spent a lot of time with that bidder making sure that the fundamental principles of rollout, migration and info management were covered, I even put one of my best guys imbedded in their team full-time for a year...but we weren't selected.....