Really? I have the latest version of FF (v28) and when I "print" a really loooooong page that requires scrolling to PDF just as you described it still only saves the visible portion of the page. I'm on OSX 10.9.2. What OSX are you using?
I'm pretty sure I tried all the FF screen capture addons and save-to-PDF FF addons and none of them work for saving long web pages and I couldn't get that Paparazzi to work either. Aaargh, I've been able to do this in the past. Saving an entire web page as an image or PDF shouldn't be this freaking difficult!
To save an entire Safari webpage as an image, you can use Webpage Screenshot Capture. It’s a free online app. Firstly, you copy the link of the Safari page you want, and then navigate to the site of this app. Paste the link in the address bar and click “Take Screenshot”. When the webpage is captured, click “Save image as a file” to store it to your local disk.