I have 2 of those. I did some of the mods on the first one, on the second I did not. I found that it did not need any of the other mods with the ATC on it.
After adding an Auber ATC all I did was put a charcoal grate in the bottom and it works fantastic.
I dont know about adding height to the legs, I dont think it would do any harm, but I dont think its needed. The thermo is very accurate
why did you change the grill racks? I added u bolts to mine for handles, other than that they are nice I think
Here is a pic of one of mine