So I asked my wife to have a look at the derailleur. She's not into cycling or whatever, but she has a good eye. She did notice the derailleur was slightly off, so I basically gave her a list to take to the LBS tomorrow. She will be picking up some outer cable stoppers and some inner cable ends, and besides that she will be checking out the price on the RD-4500-GS. If it's below €30 she will be ordering one directly, if it's above, I will be ordering through the web to save some cents.
Finally figured out how the in-line barrel adjusters work *fail* so I decided to reinstate them and make sure I have the minor cable adjustments within handreach instead of having to get of the bike every time I need to make a small adjustment. So basically, that's why I need the outer cable stoppers
