Here's what I've learned about the model year changes.
After a bit of an adventure, I bought an s-420 this past week. Originally went to buy a Genesis 320 in ss, but found Lowes was getting out of the 420 and had them on clearance for $999. Most stores were out or had floor models. Put a floor model on hold, and got 10% off, so net $50 more than the Genesis. I kept looking for a boxed one, and after a few expeditions found one. Turned out to be damaged: control panel and manifold bent. The next day I found a store with a boxed 2011 model. Actually got that one home and set up, then discovered the changes Weber made by using 430 grade stainless steel 2009 models rather than 304 grade. The 430 ss has iron in it, and a magnet will stick to it, while the 304 grade ss uses nickel. Magnet won't stick to that. 304 is more corrosion resistant and stronger than 430.
Looks like the 2009 model used the exact same design, but substituted a lower grade 430 ss. As a result, the doors, side tables, and control panel may not be as strong as the same ones made with 304. I've read about hoods making a pop when heating up, which could also be from the thinner ss in these models. I think that's how the first boxed one I had got damaged: had to take it out of the box to get it in my jeep; they picked it up by the control panel, which may not have been able to support the weight (you're not supposed to do that, I later learned, but the two kids who did it, nor I, knew at the time). That one was made in 2009 (on the door). I suspect from what I've read that some of early 2009 models got some 304 ss on some parts. I also think some late 2008 models started getting some 430 parts as well.
The 2011 model I actually took home and set up had cast aluminum on the door frames and side table frames, as well as the control panel. The SS however was all 430, except the hood door, and side table handles. I think Weber may have realized that substituting 430 for 304 ss on the side tables, control panel and doors made them weak, so came up with the cast aluminum frames on those parts to give them strength. As far as I can tell, I think the 2010 and 2011 are the same 430 ss, but the 2011 model got cast aluminum frame doors.
So, after learning this, I went back to look at the floor model I had on hold. Now armed with a magnet, I found this one was a 2008 model, made in 2007, and all the ss was 304. The side tables and control panel are cut one piece of 304 ss, cut, bent and welded ... solid as a rock. The doors are strong as well. Being a floor model, it had a few scratches, but after a good cleaning it looks great. A hundred dollars less and all 304 ss!
Hope that helps anyone looking at these grills. Weber backs them all the same, so I'm sure any negative impact from these evolutions will be warrantied.
