Karsten,
The "Quote" bbcode is part of the forum software, I can't modify it without editing the code and if I do that I won't be able to install any future updates automatically. I'm afraid you're gonna gonna have to continue adding a few "Enter" after the quote.
btw, you can put as many as you want to separate the quote block from your own text, every "enter" that you put in a message is converted to a
when the post is displayed.
Sorry, would love to accomodate you on this one but it would just become too impracticle to have to install updates manually.