This comes up every time a customer is surprised when their packings wear out sooner than expected. When I explain the different grades of paint and their effect on packing life, customers say they will switch to a better grade of paint. I try to explain that it is well worth sticking with the CHB and repack the pump more often rather than switch paint just to get extra packing life. The customer usually thinks I'm scamming him into repacking his pumps more often, so I sometimes break out pencil and paper and do the math.
As a rule of thumb, CHB is $10 per gallon less expensive than an alternative such as Promar 200. Again as a general rule, packings with CHB last about 300 gallons, while packings with Promar last about 600 gallons. This means that the 300 gallon difference in paint saved $3000. To repack a sprayer is about $200, so you're still $2800 ahead of the game. If you try to stretch your packing life, you may prematurely damage the piston and/or cylinder. This will double or triple your $200 repair bill... but don't freak, you're still way ahead of the game!