YS640 vs YS640s

So I decided to upgrade from my Traeger to a better grill. I came across the Yoders and have all but settled on the 640's. My biggest hold up at this point is should I go with the regular 640 or should I spend just a little bit more and go with the 640s? I'd like to purchase one here within a couple weeks and have talked to the dealers around me to see which models they have available.
Any help would be appreciated.
Any help would be appreciated.