Yes, the staff on the server this was built on don't have the staff to ban players 24/7. Also, if hacks weren't allowed there, people would still hack, plus, the server owner hacks too. :v
We will provide a list of what can and can't be allowed client side mod wise at a later date, as-long as it doesn't hinder security of the server, effect others experiences or exploit creative aspects it should be fine. If it can give you items you can't get normally with permissions that are on the server then its a big NO. But as we are creative, will have flying enabled in 99.9% of areas, and even then we can limit things around it with plugins that users can't get around