yes it is always safer to move your bitcoins to another wallet before importing your private keys into a fork related wallet to claim the new coins. in this case bitcoin gold.

and in case you want to dump it, then it may not be the best time to do so. the dumps are already over now and price may not go much lower than this. you may want to keep something at least for the possible pump. or sell all if you don't want to take that kind of risk.