Kind of funny but talking to 50-130 people a day on the tech line, I hear the same thing with coverage on all the brands.
Let me just add two things for you to think about.
1) making a base coat, 50-90% of the cost depending on the color is the cost of tint. Cut back 10% on the tint and it goes right to the bottom line as profit and the best part, no price increase was announced.
2) It is not your jobber as it would be suicide for him to add extra binder, only thing they could really do is cut the volume in the can 5-10% and hope you don't notice, for extra profit.
3) The Voc answer is pure BS, to meet the lower VOC's you will find those paints are normally thicker and a change of solvents.
If I was looking for the best bang for the dollar as a shop, I would be looking at the following.
Transtar low VOC.
All of these have been time tested and matches like any other paint line, good but like all lines you will always have a few colors that don't cut it.