it is a very risky move, it is upto you if you really want to run with the risk of telling your private keys to another website in order to receive a few hundreds of dollars (if you have a big amount of bitcoins)
honestly, it is not worth it, i dont know why there are thousands of people desesperated about claiming those coins.

it is obviously that this is going to be another pump and dump scenario, because bitcoin diamond is not a real altcoin, it has only been created in order to create more money, and that is the real purpose of that.