For a complete novice paddler the Eze will definitely be faster than the XT. My experience is that a novice paddler in a XT will go for the occasional swim and this keeps their speed really low. The Eze is wider which means fewer swims and thus a higher speed.
On the other end, a world class paddler in an Eze should easily be able to go faster than my 16.1km/h (10mph) in the XT, but then I'm just a semi recreational paddler. Put the same world class paddler in the XT, however, and my money won't be on the Eze.
Bottom line is, for some paddlers the Eze will be faster, for other paddlers the XT will be faster. Only get the XT if you're comfortable in it.