Having actually gone through it, I will say that it's no more difficult than any other academic internship out there. More importantly the training is fantastic. Sure the 30 hour calls were brutal, but as someone said above... the new work hour requirements will take care of that.
Getting to know the institution, the attendings, and the residents who will be calling consults into you is a major bonus. The inpatient onc service is a great experience.
As a program that is categorical, there is no option to even rank the program outside of the included internship. I can't say for sure, but I'm guessing an exception would be difficult to swing.