I used a Dex when I had the Animas Vibe pump, and now have the Medtronic 630G with Enlite CGM. My observances are both are equally as accurate, although the Enlight "seems" to be moreso. Also, with Dex I remember pretty much in the first 24 hours after putting in a new sensor, to ignore the readings. It was wonky that way. With the Enlight my experiences have been it takes about 8-12 hours for it to "lock on".
On another note, extending sensors beyond their week on the Dex was FAR easier than on the Enlite. It can be done, but its challenging.
I think in the end, theyre about equal, for the job their supposed to do, however, I prefer the Enlight ONLY because of the suspend on low feature of the 630G pump. So in short, IMHO having used both, I would feel comfortable with either.