I tried doing mine two weeks ago, and managed to destroy my passenger's side TGV sensor while wrenching off the bolts. I got a replacement, but there's no room to remove the TGV sensor with the turbo in the way.
Since I was scared to mess with the fuel lines and such that I would have to disconnect to remove the manifold, I thought it was worth a try to remove the downpipe and uppipe, so that the turbo would be free-floating and I could install an uppipe while I was at it.
Fortunately, my idea worked and the turbo cleared enough for me to get the sensor off.
At the same time, I needed to loosen my bolts for the uppipe, and the uppipe bracket, which is coincidentally what needs to be removed to access the banjo bolt.
After struggling with it for a while using a ratchet, my dad came and demanded to take a look. He then put a 9/16 on a socket extension such as the one on the far left, about 12":
http://www.toolstation.com/images/library/stock/webbig/66772.jpg
and then he was able to get the bolts I was struggling with off quickly. Pretty amazing since I'm 6'1 and he's 5'4
For ease of removal and so you won't hit your TGV sensor by accident, I highly recommend using a socket extension on the two bracket bolts. I was able to get the banjo off with a 17mm socket attached to a ratchet. If you use a socket extension and WD-40, it should take you about 10 minutes to remove the bolts, bracket and banjo bolt.
I did the string trick, except that I accessed the bolts from the back of the engine since I had the uppipe out. And I used the string trick, but pushed it in from the bottom so I was using the string to prevent it from falling somewhere obscure instead of using it for positioning.
I have 59,000 miles with 10,000 mile or one year change intervals on synthetic with stock filters or Fram (yes, Fram). My current oil is Mobil 1 with a Fram filter. I've been topping it up with Valvoline SynPower because my car was slowly draining oil, which was due to the oil bolt not being tightened all the way. To my amazement, the filter on my banjo bolt was completely clean and smelled like fresh oil. Not wanting to take any risks, I removed the filter, threw it away and reinstalled the banjo.
You can remove the filter by placing a small screwdriver or other object at the black plastic edge inside the screw and pressing down.