As Sargent said, the biggest worry is that the rewards would have to be extremely (hah) tasty. There would also have some measures put into place to ensure that people don't lower their ilvl down to 65 so they only get Garuda.

Don't get me wrong, I would like this idea and would do it given proper rewards, but there is a lot of things they would have to change and consider due to the massive difficulty gap between something like Garuda and Thordan (people would just dodge anything hard and keep going until they got an easy one).