Probably the main difference between the photos taken by your Ixus 860 and Wendy's S90 is the person behind the camera
It may not be her at all. I've not seen the photos, but I assume it's generic food photography?
If the product is stationary and the camera is steady, I don't see why a different model of camera will do better, especially since the ixus is no dinosaur.
Understand how lighting affects the photo, and setting up your camera appropriately, wield yield better results than chasing the latest camera model.
save your $$