I've seen a lot of people asking about NBT lately and you should all know that skStuff has been abandoned by it's original author for a while now (it was only updated to 1.12 by Tuke). Several people including me have said they will update skStuff or make a new NBT addon when skStuff inevitably breaks (which it will in 1.13, regardless of the internal changes Mojang makes), but it's still best to avoid it's usage when possible because its a feature without official Bukkit API support, and could break at any point. This is really only an issue if you plan on updating your server to new versions... if you forever stay on 1.8 or something then it doesn't affect you.