I have the Enlight II and, as with all Rykas for me, I order a half size larger than my regular shoe size. I wear 7's in everything but Rykas, and they are 7.5. I wasn't aware that there was an Enlight III.
I just received a pair of Ryka Enlight II's today, and they run the same way all of my crosstrainers and running shoes do. I even fit a custom made orthotic and a heavy Thorlo sock inside of them. I am wearing them for a while now before I go to the gym, and they are very comfy.
I had read that Ryka's run a half size small, so the first time I ordered up half a size (from 7 to 7 1/2) and the larger size was way too big. The next time I ordered my size (7), and in the Enlight IIs I still have plenty of room!
I wore mine tonight, and I think they run big. The next time I order, it will be a size 7. I wear size 6 and a half many times, but, in a dress pump, I need a seven. The Rykas would be better for me in a size 7.