The feed of the gun has no play on quantity of liquid used, I have gravity fed air guns with a dispensing chamber the size of a thimble. The real test of use is defined by constant flow and spray pattern. The cheap badger uses a nozzle size of 1.0 which I find too big for light repairs and can also cause spitting. For light/small areas a nozzle of 0.25 is best,the gun I showed has a nozzle of 0.30 which is just right for small to med jobs, but would take too long for suites or very large areas. The other thing to take into acount of is the constant psi and a decent compressor is a must to have a consistant air pressure, airosols are not very good and work out too expnsive,but are a good stand by for emergency use.