I've got a 30" and I've used a 3/8" granite tile and a 3/8" steel plate. I've taken both out as I get *horrible* recovery times with them. I can't explain it - I think it has to do with their thermal mass and absorbing the heat output of the element.
Anyways- the granite tile was what I gathered as the top recommendation after browsing about the smoking forums. However, I won't use it anymore. I am willing to try something thin, like the piece of "cookie sheet" I read somewhere here - but it will have a low mass.
I use a 9"x 12" Alum insulated baking tray, you can get them for under $15.
My 40" is the older model with 750w element. The first time I used the tray there was a odd smell, like something burned. I am guessing but I think the insulation sandwiched between the alum got fried. If you have a 1200 w MES I would suggest that you put the tray in for 1 hour at 275º, then smell it.
I cover mine with alum foil but that isn't necessary you can easily pop into dish washer.
My 1200w mes will not work properly with a baffle installed.
The temp sensor is 1" under shelf #3 and 5" left of the right side of cabinet.
A baffle diverts the heat away from the temp probe.
This causes the temps to swing higher and lower from the set temp.
If you are monitoring a grate temp you will find the equilibrium of the smokers
temperatures are not nearly as good after installing a baffle.
I'd like some more input about this. I might try it with a baffle this weekend. I put in my meat on Sunday and never moved it and it seemed like the right side cooked faster. Maybe I just think it did because of the comments here but it really did seem like it cooked faster on one side.
I would advise that you study the results from adding a baffle to the 1200w mes.
I did not care for the temp swings it produced when a baffle is in there.
But, everyone will have their reasons for using or not using a baffle
I also moved the temp sensor in my 800w mes from the upper left corner to the location in the new 1200w mes. I was pleased. Basically the heat gets to the probe quicker and there are more on/off cycles.
The result is a narrower swing +/- from the set point.
I went from using the older model to the 1200 watt model and so far I haven't felt that any mods were necessary. I'm very happy with the new unit the way it came. I haven't used a temp probe to see the difference in temps but so far the smokes have not indicated any need to baffle.
I am doing my first smoke right now & I'm only seeing a + or - 3* between the built in temp probe and my et-73 probe which I have on the 3rd rack on left side. This is without a baffle, so I guess all is well. Hope to have some Qview later on.