We have both iwata, sata, and the 3m pps.
The trick I've found is filling your cup with wash thinner and storing it wet. It prevents what little paint is left from curing and ruining the gun. Bout once a year we send them in for service. New packings, seals, etc...
The pps is nice, but it gets expensive. A case of bladders runs about a $100 bucks. Truthfully there's no real advantage because you still have to clean the gun. Your using such small quantities of paint so often that you burn through them pretty quick.
If gun cleaning is what kicks your but, try this. It's what my ppg rep showed me and it works pretty well.
first, understand that with a gravity fed gun paint only loiters in about 1 inch of the gun. From the cup to the horn it's a short distance.
No need to tear it down as this just leads to failure prematurely.
Dump your paint. I just hang it off the regulator into a garbage can so that it can bleed out. This works well for a number of reasons. A few ounces of paint drippings flashes the solvents off pretty quickly. The solvents are what's dangerous. Fire, fumes, etc. Allowing this to dry means you can pitch the bag and not have the guilt of killing the earth. Just be sure to take the garbage out. Cerakote is pretty harmless in this regard so it's not as big a deal. He paint stuff is a different matter though...
get a squeeze bottle full of wash thinner. You can use this instead of acetone. 5 gallons is 35 bucks here. Acetone just evaporates too fast and doesn't clean anything other than your wallet any better.
Open the needle all the way and start filling the orifice as you let it drain. Brush the inside a few times to get the big stuff. Repeat.
then flush till it runs clear.
pull the horn and toss it in your cup. Fill the res one more time with thinner. Let some bleed and brush the nozzle with a soft brush as it bleeds thinner.
Top off the cup with thinner, put the lid back on, and hang up the gun wet. Close the needle valve a bit to ensure spring tension is kept on the seat so that it doesn't leak.
3 to 5 minutes and your life is back to normal.
Hope this helps.
c.