I had a YS640 and they appear to have made several improvements. I like the new firepit design, as long as the bottom is slightly angled so that any grease drippings don't flow over into it. The armor plate over the rtd seems like a good idea, I have always been worried about smashing mine with the food grate on my pellet smokers. The plate deflector looks neat.
XL Big Green Egg, Weber Performer Platinum, WSM 22.5"