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It is a good question. On one hand, some schools offer very competitively priced programs. On the other hand, it is unlikely that folks attending Booth and Kellogg are dummies.
Here is a quick answer - the PT programs are not for career switches (Whether it is Kellogg or Dupaul). It is hard enough working and building a career while doing an MBA, let alone trying to switch or recruit at the same time. Often people end up networking with their classmates (helps when all have jobs) and often move around as the result. However, many PT programs (with exception of Kellogg I believe) do not offer career services to their PT or EMBA students and sometimes go as far as disinvite them from recruiting events, career fairs, etc since they want to make sure their FT students actually get a job since that's what the FT (and then PT) program will be ranked and judged by. Getting a job out of a PT program is never a part of the package (though some to try and succeed at upgrading).
LONG ANSWER
Traditionally PT folks have been exactly like you - they don't hate their job or industry enough to quit and plunge into the unknown but they are looking for more than status quo. What happens a lot of time is folks see or even offered better positions if/when they get an MBA - e.g. we have an opening in the next few years for a position in X dept, but we are looking for someone with an MBA, etc. That's the ideal situation, esp if you can get the company to pay for your school or at least help off-set some of the costs.
Sometimes, people take the initiative as they sense/feel that the MBA will help them no matter what. However, when they try to maneuver internally after they get their MBA, they often find obstacles - e.g. internal salary is capped at 10% max moving between positions; it is not possible to jump more than 1 level in X months, etc - I have had experience with a co-worker who ran into a wall with HR moving a few levels up (after being held back).
As to the trade off between top and bottom ranked schools - in PT world it matters less since the job market is less competitive and judged more by your experience and achievements within your fiend and your connections/abilities to score an interview or consideration. At that point the MBA is probably more of a tickmark on the resume. At the same time, you could say that a Civik will drive you equally well to your place of work as would a Lexus or a Tesla, so why are all those idiots buying them expensive cars? You get a lot more things attending a top program (higher caliber of classmates, thus access to a higher caliber of network, better professors, brand/pride, access to more alums in better/higher places, and most importantly, ability to command a higher salary). When i was asked how much money I wanted to make by one of my employers, I gave a high figure, and when it came back as to why I thought I commanded such a figure, my answer was simple - that's what my MBA classmates made, I am just looking for parity. I got my number.
Good Luck!
Congrats on thinking about taking your career to the next level!