Hi Patrick.
Thanks. No, these are standard 1 W carbon film. Not carbon composition or metal film. You are absolutely correct that any temp shift of the R's will lead to attenuation shift, errors in measurement and so on. However, it is interesting to note that just 16 of these, which would lead to 16 W pad, is actually much better than that. Two reasons, one, the PC card sandwich tend to provide a bit of a heat sink and two, the first bank of R's closest to the P INPUT side are asked to take the majority of the heat. The remaining 2 banks of R's are just loafing
I have a small fan blowing air over this little assembly and key down 50 watts, it's ice cold.
Alan