Okay, I just compared my split batch with S-189 versus K-97 and I have lots of comments now:
K-97 is yeasty, leaves a long standing aftertaste of yeast -- ick, I can still taste it 10 minutes after the last sip. The beer tastes great in your mouth, but I'm not liking the prolonged yeasty aftertaste. Haze is still noticeable after almost 2 weeks in the bottle, even with gelatin. Also a slight tartness, which I also associate with presence of yeast. All this might settle out over time. I think I will wait another few weeks to let it settle before popping the next bottle.
Other than that, K-97 also has a super creamy long standing head, outstanding retention, and a much softer creamier mouthfeel than the S-189. It also has an elegant lager-like flavor while in the mouth. Just that yeasty aftertaste I can't get over.
S-189, on the other hand, is super clean in both aroma and flavor, crystal clear, with a rockier head with much lower retention. Bitterness is far more pronounced, and I might even call it harsh. pH is on the high end by design so at this I'm not super surprised. But noticeably more bitter than the K-97 version. Flavor, meanwhile tastes like CANDY compared to K-97. Sweet-ish and cherry-ish candy. Also sort of like caramel. But also more bitter. If that makes any sense. The candy / caramel no doubt comes from my addition of 2.5% Gambrinus honey malt, which was a leftover, a couple years old, probably oxidized pretty far. I get the feeling that S-189 allows the malt profile to stand out boldly, there's like zero yeast-derived flavors or esters here, only malt-derived stuff. Very very clean.
Both beers are also noticeably orange in color, not yellow. In future I think I'll add zero caramel malts to my light beers -- that was a dumb idea.
Overall, my favorite would be... neither. Or maybe S-189. But it's still not as spectacular as Wyeast 2206 or WLP833. Just really really clean... and as such, kind of boring. The candy/caramel thing in the S-189 version is weird, though not totally unpleasant (again I think this is my fault), and the yeasty aftertaste of the K-97 is super annoying to me. Maybe I'm just overly sensitive to yeast? I mean, tastes like bread & Braunschweiger. I love bread and I love Braunschweiger... but not so much in my beer.
Bottom line: I won't really hesitate to use S-189 again. But K-97........ well..... time will tell. If the yeast gets out of the way, then I think it will be a more tasty beer. I like how it tastes while in the mouth. It's the yeasty aftertaste that drives me crazy. If that goes away, I'll be real happy with it. It's creamy, smooth, not fruity, no diacetyl, nothing bad but the yeast and poor flocculation. Reminds me so much of 1007 and 2565. I'll give it some more time and opportunity to prove itself worthy before passing final judgment.
Recipe and picture at link below.https://www.homebrewersassociation.org/forum/index.php?topic=3331.msg436395#msg436395