Ok reopened her:
No apparent damage to the sink at all. At first I was concerned about some dicoloration you may notice if you look close. I thought it may be the start of some damage. However I compared it to pictures I took of the sink pre-mod (you can see it in an earlier post) and the exact same discoloration is there.
You can see in the second image that there was some migration of the liquid metal. My family of five children went on vacation this week and the Switch had a lot of heavy, rough usage; so the migration is not a surprise. When I did the mod I was liberal with acrylic conformal coating and am not worried about the migration, though I think it is important to note.
Everything put together again and works great. I did put a little more liquid metal and thermal paste.
I was concerned that maybe I hadn't given the liquid metal long enough to damage the sink if it was going to. So I conducted a small experiment. After I cleaned off the sink from my re-open and saw no damage, I got a small peace of aluminum foil and put the same liquid metal I used in the Switch on the foil:
When I finished closing the Switch and had taken the pictures for this post I checked it:
I was stunned at how quickly the reaction happened how how badly damaged the aluminum was. Emphasizing that I am just an user and not an expert, and that my experiments on cooling effect and damage are far from scientific, I am quite confident with this mod.
It does not appear that the liquid metal damages the sink (which would mean it isn't aluminum) and the cooling effect is drastic enough to warrant the mod, in my opinion.