I know you've probably done the calculations already, but just to reiterate, going to Haas for free will save you $1,150 in loan pmts (if you were to otherwise take out a $100k loan @ 6.8%).
To pay that $1,150, you would have to make an extra $2,000 per month. After payroll taxes (7.65%) and probably a 35% tax bracket for you = 42.65% (not to mention any state taxes), making an extra $2k leaves you with exactly $1,147.
Which means if you make the median $111k salary coming from Haas, then for Kellogg to be equal money-wise (which, of course, isn't the only criteria, but it matters), you'd have to make $24k more or, in other words, 22% more than Kellogg's median which is roughly $111k also.
Plus, having gotten a full-ride to Haas, you'll probably more valuable to Haas, for good reason...and may even "shine" more compared to your classmates, vs being at Kellogg.
Great choice.