jD and j2D are not different at all.
your grab won't whiff easily too except you delay it if you do it off jB, it would be a purple throw instead except you angle upward or something...
also what do you mean by falling jB? delayed jB?
this is not a really good idea since your enemy will have ground before you do and you already used your extra jump/airdash, they can do whatever AA they want to counter you.
you might use it online or for gimmicks but I don't recommend it as something you might use often.