Density measurements of T-Grain films

I have read comments that properly exposed Tmax negatives appear to look thinner/or thicker (I can't remember) on a light table that a TriX or conventional film. Some of the bad reviews these T-Grain films first received were because people would compensate exposure to get a similar looking negative and thus block the highlights.

My question is: How would this difference effect density readings to determine fb+fog and other zone system/BTZS measurements? Are the threshold densities the same? (even though they may look different to the eye).

I hope I explained this correctly. Just something I thought about today.

I think this is due to a lower base + fog reading making the whole negative look thinner. Acros is certainly like this. Since it is the density range and not absolute density values that determine how a negative prints I can see how people could get messed up with a new film that has a low b+f value.