i have both satas 5000 digital in hvlp and rp in 1.3..
RP in 1.3 is a hoser and sometimes "too much" for everyday daily drivers oem finishes, hvlp is true to size ib 1.3 and outstanding....
i did not try new 5500 yet...
"I" pattern has been perfected by Iwata guns....Iwata has not released a new gun design since Supernovas ....so they are onto something with their wicked tulip design...the only critique of Iwatas is the lack of literature or suggestions on how to set up their guns from designers of the gun, sometimes it is time consuming and frustrating..
another spray gun that has outstanding I pattern, speed and superb atomization is German made Optima Trifity/Trinity 1100 lvlp with AS/Pro/"rp" air.cap....
I find Optima better designed, better ergonomics, less plastic parts, easy to use, true analog gun built in gauge, simly more robust gun than Satas...