I don’t remember exactly what was going on in the other thread but I have no impression anything was personal.
I can only say, try to keep the restrictions minimal and gameplay-focused. If you require a specific 7DS item that has most likely no gameplay reason and instead, while it might add style, is excluding non-7DS owners from the contract. I know IO had such a contract in their own batch but I would not take that as an encouragement.
You can also aways check this thread in case there are helpful ideas to find: