I have chosen to not do anything but x000 Genesis, "Fat frame" Genesis, and maybe once in a long while a 1st generation or 2nd generation (Platinum only) Summit.
If I get to semi-retire in a couple years and decide to do 300s again, I will only do that if I can get a run of stainless bottom and backs made at a realistic price. Without that, those grills are too susceptible to rusting out again after working hard to restore. New stainless panels make that a simple part swap. I had a small run my friend in Florida made for me, but that grill had my last set. It was going to be another keeper, but I finally realized that I just can't keep EVERYTHING!!!
I found a nice shop nearby me that has the specialized cutting equipment and was willing to make a run of those panels at a fairly realistic price. I don't remember the specifics, because I couldn't come up with a realistic way for several of us to go in together. Shipping makes something like that impossible.