I had a 2.4 200 Brera for 2 years / 32000 miles, some of they with a remap, some without. I kept a spreadsheet logging date, milage, quantity etc. The remap made no difference to mpg. Every week I'd do 100 miles motorway on Monday, 50 miles urban during the week and another 100 miles motorway on Friday. Average mpg over two years was 28.
My DPF was a nightmare both with and without the remap. I concede my experience is not typical and that I had something of a lemon - it first went into limp mode with 14 miles on the clock. The first few thousand miles had several DPF related limp modes. Then I had about 20000 trouble free miles. After that the engine frequently went into limp mode on a friday, often clearing itself about 6o miles into the motorway run. If I had to have a diesel again (and it would take a lot of pressure to convince me) for both mpg and reliability reasons, I'd think very seriously about DPF removal.