I play both instruments, and they both help out each other in some way or another. As far as technique, there is no comparision, they are two seperate things, but has far as creativity: playing the keys' help with the bass and the bass helps with the keys when i play. But like i said, technique, you're using different muscles in your hand and wrist, just like playing basketball and soccer. The only benefit is probably using all the muscles in your wrist, hands, and fingers.