It's been almost a year now since I purchased my second Travelite Delite, one of the bags which started this thread.
http://www.travelite.de/starlite.html
To recap, I had purchased the original version, which flew many hundreds of thousands of miles, was checked multiple times, and regularly travelled on trains and the metro, and was used to walk over cobblestoned streets.
When the zipper began to pull away from the main part of the bag, I purchased the second incarnation of this bag, and was not entirely happy with the changes in design.
Version II has travelled in a similar fashion, albeit at least 100,000 miles less than Version I, and was rarely checked.
This week I had zipper issues again.
I believe that it is a design flaw. I never overstuff the Version II (almost impossible to do so due to the lack of an expandable gusset). The issue seems to be that the unstructured style of the bag results in the zipper not always moving in a straight line, which eventually results in it pulling away from the frame.
I'm very disappointed after this bag was such an initial success. Perhaps it just isn't made to withstand the ultra travel in which I engage. At this point I may consider paying to fix the zipper on version I, rather than buying yet a new bag. I may also browse Lipault as the January sales are coming up soon in France. I suppose that if I end up with something I don't like from Lipault, I can always gift it to
chollie 
And by the way, it looks like this may be a decent price for the American readers?
http://www.amazon.com/Lipault-Marsei.../dp/B00632UC8O