I can only speek from my own experience, and that would be as an Shiatsu therapist. It depends how well the program is done. My school was International school of shiatsu, and the school lasted for almost 5 years!
The basis for traditional shiatsu massage is TCM, and therefore, you have to learn TCM to be able to understand the principle of aplying the shiatsu.
After that, you will learn Zen shiatsu, which also rely on TCM, but also applies new things, it learns you to feel the energy, rather than to apply specific touch on some ACU points to treat the problem.
You will also learn basic rolfing routine, as well as some osteopatic treatment, energy treatment, and even more, if you are willing to participate more.
So, you should ask for a more detailed program of both of schools, and try to see what interest you more. It's your desicion.
Best of luck!