The peels seem like they may add some tannins or some type of astringency, (in a good way). I've only made 1 gallon batches of orange vanilla melomels, and I did use 1 large orange and just a small bit of the peel. I really dislike regular oranges, but for some reason I LOVE cuties. I think they are less acidic maybe? I also dunked the orange in star san for a few seconds to kill any wild yeast, probably unnecessary.
Here was an orange blossom honey batch I did with the orange as mentioned above, maybe you can tell a little by the color of it. I just has a slight hint of orange taste, you wouldn't know it was there unless someone told you I think.