Buddy sells upfitted RR trucks and his is based off of net profit, which is a constant fight. Reason being, he is spec'ing a truck and with 40 different component packages going into one unit, he has to configure and price each thing accordingly within their structure to make sure there is a profit, and if done correctly, there is. Then you get paid, handsomely. Reward for good work.
I will say, going from gross, to GP, to NP, if you drop the price to get the sale and you're a total gross percentage commission, it affects you much less than if you drop the price on a profit structure.