Baselight houses I worked with seem to prefer EDL over AAF, and the short test I did some years ago showed that the resize info did not get across in the AAF (the Baselight would not pick it up, or not correctly).
I usually add timeline comments to the resizeds shots (red segment select, record monitor menu, Add Comment). i type in the percentage. When creating the EDL, I tick the “Clip comments” box in the options. This adds the comment to the event in the EDL. They will then know which shots to resize. They will then manually redo that resize looking at your offline reference
I always ask that they don’t have the Colorist do this, but rather a conform editor. Many, many things can and do go wrong when conforming, and top many people rely on auto-conforming, only to find out that there are tons of issues with speed changes, resizings, etc. Good conform editors tackle these issues.
Then, because I am a control freak, i ask the conform editor to send me a QT or MXF export of the conform, and I then gang my offline and this new file in the source and record monitors, and check each shot for sync and applied effects. Depending on the dedication of the conform editor, i then usually find between 1 and 5 errors per reel, much more if they did a lousy job. Time consuming, sure, but it makes sure that you get what you intended.