I did a flush on mine the weekend before last. It passed the "serviceability" test before I did the flush. I didn't have any ride-quality issues going into the flush, so there wasn't going to be much of a noticeable difference once I did the service.
I'm doing the same thing you are, I'm going to keep it as-is too. Unless the system starts to fail or turn into a money pit, I'll likely keep it that way longterm.
Since this is replacing the S3, is the truck going to be your DD? Any future plans for mods?
Yeah this will be my daily. Aside from lights and maybe rear drawers I don’t ‘plan’ on any mods...we’ll see how that works out.