I have the sit and climb. It is a great stand, they lock onto the tree and are solid. It is very light, and very easy to use. It is not the most comfortable stand out there. If comfort is the most important go with another brand. Not made for sitting all day, that said, I have not tried the newer seat so that may be an improvment. The only complaint I have with the stand is how narrow the seat is. If you are a bigger guy the seat is going to be too small. When it gets cold and I have insulated pants on I barely fit between the seat rails and I'm not that big, 6' 0" and 210. I think the newer stands have a wider seat as well.
If you want a stand that is light, easy to pack and use, dead quiet, and rock solid on the tree there isn't a better climber made IMO. If comfort is the most important feature go with a Summit. I really like mine. A cheaper model cost me a nice deer with an ill timed creak when drawing my bow. That won't happen with a LW.