Are they pretty much all alike or are some truly better performers? I mean all stainless, double wall vacuum, not plastic or glass lined, and not insulated in some other cheaper way. I want to brew pot of coffee and have it stay hot all day. Right now I'm leaning toward getting an old Uno-Vac in pristine condition, but others like Stanley, Nissan, or Thermos and claim they are superior to anything else. Confusing. Then there are the no-name China and Korea knockoffs although I'm sure probably all thermoses are made there now. Really need somebody like Consumer Reports to actually scientifically test them under same conditions. Ideally you would think if vacuum is acheived then size of stopper and insulative value of stopper would be only difference since that is where heat transfer is going to occur. In real world there probably are performance differences not accounted for by this. Thanks.