Appreciate the reply and glad to hear that I may not be completely crazy or off track. I think the version of the RIP I use is based on 12, so backpedaling isn't a possibility.
My quality issue is probably so minor and relatively specific that I wouldn't be surprised if it never became a bigger issue for folks. However the fact you specifically mention SO Diffusion does make me wish I had some profiles to try that were not using it—They all seem to be. This printer does not have the market presence the larger ones do so there's not a lot of off the shelf profiles available and I don't have the ability to make my own at this point... but may have to think about changing that faster than I planned to.
Thanks again for the reply.
Go download profiles for the 1324 and 1624 if they offer more profiles online than the 628. Store them in a folder on your desktop. Next go into Flexi system folders and find the folder for your 628 profiles. Copy and paste that folder on your desktop too. Now delete ALL the 628 profiles inside Flexi system folders you were using and paste the 1324-1624 profiles in your Flexi system folder for 628 profiles. You printer uses the same print head as those machines it just slower which is firmware controlled so there is a chance those profiles could work as well. After all that go try to print and see if it works for you.
The next option is to sign up for Flexi subscription but use version 12 and not 19 for a month. Use the profiler wizard to make your own profiles using the 1324-1624 Profile ICC data. The wizard has an option to create a fresh new ICC profile that you either scan your color charts or import ICC data. Just act like you are making a new profile for your 628 and on the steps it ask to scan or import data just use the 1324-1624 icc data as they are just chart measurements. I have done this with Roland printers. The profiles I build on a really old SC540 will work on a Roland XJ/XC540 for example using Flexi 12. You are SOL though on Flexi 19 cause they stopped SO Diffusion. I had to call them and get switched back to 12 with a download link so be prepared to make a call after signing up for Flexi cloud however it beats paying $2500 for a RIP and $2k for a measuring device.
IF none of that works I actually have a like new Xrite iSiS 2 Chart reader for sale on here for $2200. It will plug right into Flexi and you can make your own profiles in Flexi. You can use a cheap hand held xrite but they tend to error out scanning patches and will take forever with the huge 1500 patch color charts and I just don't trust them after using the chart scanners.