Hi Ray L,
IMHO you are right that minor variations in tempo is part of the overall dynamics in a band. Setting the tempo is a bit more tricky, though. That is why a near perfect count-in is important. Maybe I have just had the misfortune of meeeting too many drummers that did not care, if they played 120 or 150, but of course noone is wishing machines here! Alterations from 125 to 130 can often be enough to spoil a song or make it difficult to interprete the words - not to mention if you go to from 125 to 140. On the other hand for some songs it really doesn't matter. I also play a bit of drums, and being a drummer, one often doesn't think about the difficulties a singer may have giving meaning to the text and feeling that it is swinging (the same goes for lead guitar). Singing a tune is more than just belching out the words, and playing it is more than just hitting the right notes. This feeling for a song is very tempo dependant. But maybe I am just too sensitive?