Ok, two solutions: A coworker of mine that worked on the Dashboards helped me with the first answer to this question. Basically, you have to clear all charts, then iterate through ea. chart in a particular dashboard (stored in the DB), and rebuild ea. chart w/ your decision to have or not have a dataLabel, placing it back in that dashboard; but I wanted to avoid this as it might take a performance hit.
Also I later got a response from Pekka of the Vadding team, as follows:
'You can easily hide the dataLabels with basic css. For example, if you can apply a stylename "dataLabelsHidden" to you UI, then you could write in your stylesheet a specific enough rule for hiding the labels. I quickly tested the demo with this:
.v-ui.dataLabelsHidden g.highcharts-data-labels {
display: none;
}
This way you won't have to update all your charts when the labels on/off is triggered.'