I have a Hanna Alk and a Red Sea Alk driptest. My Hanna is always 2dKH higher than the Red Sea result.
I tend to think a driptest outperforms a Hanna bc Hanna is looking electronically at a color range and electronically calculating against a color chart in its firmware.
A driptest changes colors within 1-2 droplets.
I tend to believe more in a driptest that chemically changes colors right b4 my eyes
I also believe most testing only tells you a range +/- 5% and not to be interrupted as an absolute value.
So Hannas will tell you basically what's going on in your tank in a narrow enough test result to act or not react to the test#
Example: if I was only working with my Hanna Alk and it read 11.7....I would say, "huh, alk is a little high". If it came back 14.7 then I'd be doing a high volume water change. I know the test# isn't the actual# but close enough to know when to react