I studied through Book Two with Craig in EIS. Craig is an excellent teacher, composer, guitarist and human being. If you have an honest interest in EIS, I would recommend that you speak with him. He has taught many people, and can both demonstrate and apply all the techniques professionally. He was always helpful to me and my progress as a musician.
I am about 1/3rd done with the main composition course in MITA. I have a financial interest in neither.
They are indeed very different courses, as Craig indicates. This difference extends from intent, to organization, scope-and-sequence, approach and even to the way homework is done. They are not "fungible" to use an economic term. They are different things and produce different results - having different aims.
Both are long term investments of time, money, and life energy. They are not "for everyone", in the same way that university study is not for everyone, or any other activity you might imagine. But for some, they are an ideal pathway. Only you can decide that.
Both sets of instructors will patiently spend time with you to assess what you are looking for and if it will fit. Both are big enough commitments that you aren't going to want to make them off of some random forum posts. You want to speak directly to the responsible parties.
I have found the right pathway for my development in MITA, but I use the voice-leading I learned in EIS every day. My familiarity with EIS basics made shifting to MITA quite easy. These are rigorous courses covering concepts that are not part of an undergraduate music theory/composition track. These courses are taught inside of a mentorship, personal-relationship model - not dissimilar to how Nadia Boulanger held court in Paris. Yes there are exercises, but they exist in the context of a relationship and effort to apply the concepts practically.
Both courses are the opposite of an instant-gratification mindset of watching a YouTube and winning an Oscar 5 min later from a "hot tip". They are for the curious, the hungry, and those who didn't find all they wanted through traditional coursework. Most of the students in both are working professional musicians with formal training and degrees. That should tell you something. They aren't re-buying information they got in University.
The real question is if you can write everything you want to be able to write given the training you have? Would learning an alternate approach to thinking about the same 12 notes help with your journey or do you already know enough to do everything you want to do? Do you need or want mentorship in developing as a writer? Both courses offer solutions to that problem, though definitely framed differently in each case.
If you go to Facebook, and watch the current round table discussion, you can listen to one of the compositions I did months ago, and see what my completed homework looked like at that time, and hear my explanation of how it was done. Naturally, I have progressed since then, and am more capable, but it is a data point from my journey. That is probably more useful than anything I could say here.
Learning systems that promote hard work over a long period of time are very popular with some and deeply unpopular with others... As this thread may illustrate before it is complete. But both courses are run by professional, competent, delightful human beings for whom I have enduring respect. You should ignore the trolls if they appear here.