Actually -- as a current McDonald's Canada employee, I can tell you this:
Fresh, whole, Grade A eggs are used in the McMuffin sandwich line, liquid eggs from a carton are used for the scrambled eggs (part of the Big Breakfast... something I believe the American menu does not include?) and the folded egg that comes on the Bacon and Egg Bagel and McGriddle sandwiches is thawed from frozen and heated up on the clamshell grill before placement in the sandwich.
This powder stuff you speak of does not sound attractive at all. I guess that makes just one difference between the American and Canadian McDonald's menu.
I believe the way it works out is, if you remove the slice of cheese and ask for no margarine on the English muffin, the 12g of fat is reduced to 5. The Egg McMuffin is the healthiest breakfast sandwich item, nonetheless.