Ajoten-
The LJ 5500 is outstanding and appropriate and the 6600 is as good. However, for shift quality an LJ 1000 with delrin and alloy or an LJ 4000 works as well. The advantage of the 1000 is that it is cheap but shifts as well as the 4000 or the 5500 although it is slightly heavier. The 4000 is lighter than the 5500, if that makes a difference, and was the actual derailleur the Peugeot team used in the Tour de France. As well, the black and silver looks really good with that period of Peugeot.
The LJ 5500 is outstanding and appropriate and the 6600 is as good. However, for shift quality an LJ 1000 with delrin and alloy or an LJ 4000 works as well. The advantage of the 1000 is that it is cheap but shifts as well as the 4000 or the 5500 although it is slightly heavier. The 4000 is lighter than the 5500, if that makes a difference, and was the actual derailleur the Peugeot team used in the Tour de France. As well, the black and silver looks really good with that period of Peugeot.