I don't think that anyone without a chemistry degree is going to be able to say for sure. Rusts are ferric hydroxide : Fe2O3.H2O or similar. The technical paper below lists ten different forms of ferric hydroxide. Goethite is the most common rust on rusty steel parts, according to the article below. Compounds don't necessarily stay in one state after the chemical change. They can, if conditions permit undergo further chemical changes. The Wisconsin extension office article states that if microbial activity is sufficient to decrease the oxygen supply in acid soils, some ferric iron oxides and hydroxides will be transformed to more soluble ferrous forms. I think that it is more accurate to say that none of us really possess the knowledge to state conclusively. I will ADMIT that I do not know the answer conclusively. You are going to have to study some of the technical papers and decide for yourself. Here is a link that might be useful: Iron Oxides and Rust

Alek, I enjoyed looking at all the info on your web site. Recently I saw a NG Y0660 that had been returned to Sam's Club because the buyer really needed the LPG version. It was a bit dented-up in the front, and missing the rotisserie parts. Sam's wanted $700 for it. I started the task of trying to figure out just what it would take to convert it to propane and to repair the cosmetic damage. When I realized that the valves would have to be replaced, as well as the orifices, both doors and one drawer, as well as all the missing rotisserie parts, I almost bagged the idea, but decided to call Grand Hall and check on parts prices anyway. Am I ever glad that I did! The prices were so reasonable that the total cost to convert to LPG and restore the grill to new condition was only $270.00 including shipping. When my offer of $500.00 was accepted by the manager at Sam's I picked up the grill and ordered the parts. I've installed them all, with the exception of one valve that was not correct, a missing bracket to mount the rotisserie motor, and slides for the tank drawer ... basically just "noise-level" problems. Haven't had a chance to use the grill yet, as the weather hasn't been too cooperative, but I'm looking forward to it. My total cost for an "almost new" Y0660 grill is now $770.00. ! ! ! ! ! ! S C O R E ! ! ! ! ! ! There are a few things that I've learned from this exercise that I'd like to pass along: 1) Grand Hall's customer service folks are great! Their policies are pretty good too ... with the incorrect part it was "Oh, we'll get a replacement out today", not "Send it back and we'll see ...". 2) If you know what you need, and how to ask for it, you *CAN* buy the parts to convert these grills from NG to LPG and from LPG to NG. 3) The parts costs are ludicrously low ... the main valves, which include the orifice are only $5.00 each, and the side burner and rotisserie valves are $8.00 each, as they include a little more hardware. It probably makes more sense to just buy the darned things than to do the drilling for the LPG to NG conversion, and it's WAYYY better to buy for the NG to LPG conversion than to try filling and redrilling with smaller holes. 4) Rather than actually replacing the valves, which can be difficult to get off the manifold of the Y0660, it's better to just swap the valve cores and the orifices. I don't know for sure if the valves are common between the Y0660 and the smaller Y0101XC, but the conversion pictures on your site look identical. For example, the main burner gas valve part number is P03222007A for LPG. Also, the valve bodies have the number "0404A" cast into the side. This is the same for the NG and the LPG valves. How does this compare to the part number & valves for the Y0101XC? I have a full set of parts for anyone wanting to convert from LPG to NG. I'd also be interested in that guage that you've got left over from your conversion,...

I am also considering a grill pan or double burner grill. (I'm using gas but all four burners are differnt) America's test Kitchen rated grill pans, and found non-stick aluminum to give best results. You might want to check this out. Also I have seen closely related "panini pans" which have a press included. Has any one used one of these for anything like bacon, sausages, etc?

CR isn't the be-all and end-all particularly with high end stuff. Those focus more on "value" and they don't usually see the value of high-end appliances. Looking at your list I think you've got good choices except possibly for Viking. I'm not speaking from personal experience but on the appliance forum there have been a lot of complaints about Viking reliability and service over the years. The one other thing I would point out to you is the marble etches and will develop a patina over time. You can seal it from staining but not etching. As long as you're aware of that and comfortable with it, you should be fine.