Yeah, I have heard that about Spirit Class. Looking at the Panamax dimensions (as according to Wikipedia), Carnival's Spirit Class just barely fits in the canal.
The design of Dream does look interesting. Those Cove balconies on the lower decks seem like a neat idea. But what about if they sail through rough conditions? Sometimes those waves and swells along the Gulf Stream, especially if there's a hurricane or tropical storm hundreds of miles away kicking up surf, can be higher up than the lowest one or two passenger decks. Unless they're not that close to the design waterline.