What is he saying? any strong preference(s) what visit days has he been to?
In general I am in the financially conservative camp.
In general I believe that there is such a thing as an engineering temperament, and that all of the places on the table with have that within the engineering school.
BUT… I also believe that MIT is a distinctly different place, with a particularly unique culture, and that they are usually pretty good at identifying their own.
So, IF he went to the revisit day and IF he has a strong preference for MIT after that and IF you can swing it with just the usual loans (approx $27K total) then I would encourage that path. Sometimes it makes sense to go for the brand name.