The higher the wattage the better and dont go for a unit below 500,600 or 700W this is something we are hearing of a lot, Machines should not be marketed in this context as it is misleading the higher the better we have been told. This is incorrect. The wattage of a unit is simply the power consumption and amperage of a unit dependant upon type of motor being used, motor 1 may be more economically friendly, better quality and design (such as turbine as oppose to a standard rotary) and only 400w but give the same airflow output as motor 2 which is less economically friendly, Not as good design motor, but is 600watt.,, Alternatively both machines may have the same quality motor one 400W and the other 600W and as they are the same motor just different wattages then yes the 600W will drive more airflow so maybe the pressure on this unit is to high to spray ? ,,or it may have low medium and high setting as to which the latter never get used due to the pressure being to high so in this theory is there any point in having a higher wattage motor ?. The Earlex ts-50 and hvlp 5008 have been a market leader for a while, at 400w,
Guns require regular cleaning and maintenance, as to prevent blockages as needle sizes are more optimised nowadays generally many around 0.5-0.6mm needles this optimises solution output more into a fine mist when oxygenised as oppose to more of a liquid droplet,
thus creates a more flawless coverage with less drying time and optimising solution useage in the process, The Down Side of the needles and tips reducing in spray machines in size from 0.8-1.0mm a couple of years ago is that solutions when left crystalise and with professional units being a smaller output can more easily block when correct maintenance is not carried out and guns not cleaned as the output holes are smaller, We Cannot stress enough the importance of spray gun cleaning and maintenance and the understanding of the particular spray gun you choose as to fully understand how to remove the airflow nozzle and tip to clean the spray needle. Blockages in the guns, restrict solution output from the gun, sporadic spraying is common in this instance such as stop start in solution coming out when the trigger is pressed, Also the needle sticking even when the trigger isnt pressed so continuing to spray,
it is important to clean the filter regularly as to allow the correct airflow into the motor, if this gets blocked this can cause the output air pressure to drop 
