As was said, you will have to do an internship somewhere else. I applied to several 2-4 year programs, interviewed at one of them and then rapidly cancelled the others. Not that you can't learn something from a transitional year, but I felt like it was definately *not* the best way to spend a year of my life. And if you end up wanting to fellow in something doing 4 years of residency ends up making a long haul. And I am not sure that the things you do learn necessarily equate with better EM physicians. Knowledge is never a waste but......
Also, although some 2-4 programs are going to 1-4's, the majority of EM residencies are still 1-3. I think its something like 85%. So, I find the arguement for 4 year programs (which coincedentally tends to come from 4 year programs) are better is a little insulting to the majority of EM trained physicians.
I intend to go academic, but I don't think a four year program gives you a better academic background. A fellowship on the other hand does.