Advantage to have Kung Fu background for BJJ guys:
- The stand up throw can set up nice ground control.
- Strong head lock is powerful in side mount.
- Strong grip strength can help the ground game.
- Using leading arm to jam back arm strategy is very useful in ground game.
- Kung Fu skill can help you to get back up on your feet quickly.
So, I had another thought, after reading this thread again...
After doing BJJ for a while, go back and look at your karate katas. You might find a bunch of things you haven't seen before. I started Karate after doing Danzan Ryu for many years. When we are discussing the applications of the different karate kata, the karate guys see some really nice punching, kicking and elbowing things. I see throwing, locking, choking and grappling moves. Learning a new art can allow us to see things in our first art in a whole new way... But you do have to look for it.
Depends on the style. In the kungfu I learned, we sparred with sanda ruleset which allows takedown. This has good crossover.
General fitness and grip strength.
Your ego- this may affect you differently depending on how long you have been training and your general attitude. You'll have to swallow your pride as you get rolled around and submitted by lower ranks, in the same way you do when sparring with new people in your style.