Well, hmm, ehh,.... of course anybody can have whatever opinions they like. As someone said "you can have any opinions but you can not have any facts". But of course you can ask about any facts, especially here at talkstats. Someone said that they wanted this to be a very frindly place. But it has happend that not so polite words have been said. (I am one of those who have been accused of beeing rude.)

About MVTR: If you measure that with the slope, then of course the slope parameter is of main interest. Then of secondary interest is the standard error in that slope estimate (the "uncertainty in the slope"). When you do a regression model it is of course the standard deviation in the residuals that is of interest, not the standard deviation in the original measurements. The engineer is a little wrong about that.

But isn't it about what is a good model and good descriptors of a model? A good model is a model that fits to the data.

In this case, doesn't the data converge to an upper asymptote of the sorrounding air like: L(1-exp(-b*t))+epsilon, where L is upper asymptote, t is time and b is the slope and epsilon is a random term.

This page says you should consider temerature and moisture around the sample.