ACGME-I means that the international program was reviewed by the ACGME and found to meet all of its standards. When this first was announced, I thought that the ACGME would then lobby for states to allow ACGME-I training for licensure, but that has not happened. The main benefit of ACGME-I training, esp in IM, is that with it you can apply for a US fellowship without redoing a residency. Fellowship training counts as US experience, so you can get a state license to practice with it. I don't know how successful ACGME-I grads hav been at getting fellowships, but for the low competitive ones (Nephrology, ID) I expect it would work.