Frequently asked questions (or stuff you should just know)
The short answer: Datapacks that use functions can run 1000s of commands/second which is very costly performance-wise
The long answer: That really depends on what kind of datapack you are talking about. Some datapacks (the much simpler ones) only modify loot tables, or add simple advancements, or add recipes and those datapacks are totally fine for use on servers where performance is a concern. In fact, I'd argue that datapacks do those simple things better than a plugin could. BUT, some datapacks make use of functions which basically just run a group of commands, and they do that every tick, for as long as they are loaded. This can result in thousands of commands be run every second changing or reading the state of the world, and that can have a serious effect on performance. This plugin uses the Bukkit API's event system to dramatically reduce the cost on server performance.
Some datapacks, like graves, stats, or home have stored information on the server, like grave locations and items in graves, or home locations. At the moment, there only exists migrations for statistics. So if you remove your graves datapack and enable the Graves module of this plugin, existing graves won't work as expected. Same for homes and other non-stat datapacks.
It's possible in the future, migrations for other datapacks might be added, but for the moment, they don't exist. So I recommend, if you don't want to lose data, keeping those datapacks, and just using other modules from this plugin.
Other than that, its as simple as running the uninstall function for the datapacks (should just be
/function #vanillatweaks:uninstall). Then disable the datapacks, add the plugin, and restart the server.
For a serious environment where people might get mad at you if you configure something wrong, make sure you take a backup of your server before disabling/removing the datapacks and adding the plugin in case there is some unexpected loss of data. Feel free to inquire about possible issues migrating to this plugin in the discord.