I'm not a Zuca Pro user; however, I will tell you that Lufthansa is *very* strict about their carry-on policy.

This happened to me May '2010:

Leaving IAH, they didn't seem to really care--it was their 747 and I was in first. We landed in FRA attempting to connect to ATH and they basically announced that they were checking all non-personal carry-onbags. (i.e. laptops, purses, etc) I was in Business, boarded after 10 people and the GA stopped by because of my (small )rolling case. It was well under the size and weight and at the time contained my camera and various expenses lenses. Standing in line I basically had a 3 min conversation stating this bag contained camera equipment, could not be checked, and almost had to open it up and show her before she 'exampted me' and waved me on. Then.... As I'm putting my bad in the overhead, a woman out of nowhere pops up and grabs a FA and says, "How come he gets to bring his bag on" and almost makes a scene. Luckily for me, the FA blew her off and said, she didn't know, it was up to the GA and that was that.

After the door closed, there was a ton of room. Basically, everyone's personal items were in the overhead with room to spare and nothing under the seat in front of them, so I don't know what the issue was.

Bottom line: My bag was under weight and size, and the GA decided to force check non-personal sized items for no apparent reason. I would not tempt the LH GAs.