I agree with both of your analyses, and while going through the pains of installing this system may not result in outrageous gains, do you think there will be any harm to these diesel engines? Even without a guarantee that an intercooler would increase the performance of my car, I would probably do it anyway because it gives me something to do
That probably isn't a sound reason to spend a lot of money, but these cars break down so infrequently that I rarely have any good projects.
Alex