NOTE: This is refering to a sequence that you know has no flicker.

So I wonder what would happen if instead of doing the normal copy and paste of your develop settings as per each stared frame--you just copied and pasted / Synced ALL the images--Then Auto Transed it?

Nothing will happen. If the key frames are same, the autotransition will just connect them linearly like if you would synchronize in Lightroom.