Most programs are accepting either the AOA CORD standardized letter OR a traditional LOR this year. The programs that traditionally required the supplemental eval (Wash U, Vandy, Brown, UW, etc) seem to be mixed on whether they are requiring the new AOA letter or still accepting the old supp eval form. The only program that I have heard REQUIRING the new AOA letter is UW. Many program websites have updated info on this in their "How to Apply" tab re the new AOA SLOR. Regardless, its the first year that this is being rolled out, so I highly doubt that any program will be hard line on this.
The idea behind this new standardized letter is to make the process easier for both the applicant and the letter writers. If the writer can skip all the fluff about rating/ranking you and just check boxes and then add a personal blurb at the end, they are much more likely to be enthusiastic about writing your letter.
Some of my writers only filled out the AOA form w/o attaching a "Traditional" letter and some filled out the AOA form and attached a traditional text letter. I sent AOA form to all programs regardless of whether they do/did require it.
