I've driven a re-mapped GT more or less back to back (well, about 2 hours in it) with one fitted with the autodelta box/resistor mod (mango's).
The re-map made a much bigger/better difference than the tuning box.
All depends on what your after. If you want the most power then it's a re-map but if you want the flexability a box gives, i.e it's removable/switchable then go for the box.
I believe "AL's" came back at about 195bhp on a 159 with a box?? Was the DPF still there?? Amazing result if so as AFAIK, the DPF saps quite a bit of power.