As a new rider, I put too much emphasis on parking-lot "feel". This can lead to over-inflating the tires. The "feel" in the twisties is more important, which is mostly a matter of suspension feedback that inspires confidence as opposed to the kind that tightens the sphincter. (Of course, the latter shows up with over-confidence regardless of the tire pressure.)
In this regard, Progressives out-perform stock springs, whether sagging or not. Air caps are an 80's technology that I'm happy to dump. It was originally borrowed from motocross, where it still crops up from time to time. (A few years ago, it cost Marvin Musquin an AMA championship.)
Progressives perform better when you periodically bleed off the head-space pressure, especially when getting frisky on hot days. I'm sure cartridge emulators are better yet, but I'm likely not a good enough rider to realize it even if they aren't overkill on an XII. These further manage compression and rebound damping -- I understand that they can be a PITA to dial in. I mean, suspension tuning is a black art beyond just keeping the suspension off the bumpers and beyond just fussing with the headspace air pressure.
For a piggly touring bike? Yeah, I'm sure the OE forks can work plenty good-enough. I highly recommend Progressives in the forks as a cheap and effective upgrade, especially since you probably need new springs anyway. For the back, I'm amazed at how well the stock shocks perform with fresh oil. I'm all-in with keeping those until they leak -- they aren't rebuildable in any practical sense. I could see dumping the stock shocks, but that usually means having to get new shocks just to change the oil.
For tires, I'm a big fan of Pirelli MT66, which are also old technology that I think compliments the XII suspension nicely. But I'm running Shinko 777, which seem to perform almost as well and last longer. New tire technology also is a black art that might not play well with old-tech XII suspension.
YMMV