Thanks for posting this Ken - pretty interesting data. I think I only see one SPS tank that is running "high" Alk (11). I also recall this being a "thing" for a while but seems the trend has drifted back toward levels more in line with natural salt water.
Interestingly, I have had an experience similar to Holly's with regard to calcium levels and Kent salt at target Alk although have, so far, avoided any precipitation issues. I'm currently running 8.3-8.6 on Alk with fairly high (500) calcium as this is where it stabilized with my CA reactor dialed in.
As to the original question (uptake rate vs. Alk level) seems like there have been some good idea/advice/theories posted - wonder if there are any actual studies done on this? Would be a bit tricky to do accurately I would think once you try and control for everything. You would need to measure/track the biomass of the coral and keep the target Alk constant as well as figure out a way to measure uptake either directly (tracers?) or indirectly (replenishment rate). Probably more work that anyone has been willing to dedicate.