I personally hate the BK5 action. I can't play with this keyboard.

I prefer 1000 times the low end psr keyboards.

They have the advantage of being very well scaled to the velocity.

If I play a little bit harder, it will sound the same amount a little bit louder.

With the BK5, playing softly will give you a very soft sound, and then playing a little bit harder is still soft. And playing harder is switching to a too high velocity.