Do we need to revisit this yet again?
Nobody should expect a $150 (or $250) colorimeter to outperform a ~$750 10nm spectro.
Nobody should expect a $750, 10nm spectro to outperform an $8000, 5nm spectro.
Meters will drift over time. The only question is one needs to answer is how much one is willing to spend for a certain level of "surety."
One can certainly make the case that a "professional" calibrator will probably maintain their instruments better that the average home DIYer.
OTOH, one could make the case that a "professional" calibrator is time constrained and may not necessarily be able to wring every last drop of improvement out of a given display versus a home DIYer who (at the very least) has the advantage of being able to experiment on their displays at will.
For my part, having lived through the era when Optical Comparators were, in many respects, considered superior to colorimeters I find these arguments a wee bit amusing (and sometimes tedious.)
There's no black and white answer here, only shades of gray.