Oliver Arend wrote:
After reading

http://www.faa.gov/aircraft/gen_av/l...dia/Zodiac.pdf

I'm wondering how much trouble is hidden in other kitplane designs?
Obviously, the RV fleet seems to be rather untroubled, but the others?

It is not untroubled. Besides the nose wheel issues already mentioned by
Ron Wanttaja, about three decades ago the RV-3 experienced at least four
accidents in which in-flight wing separations occurred, and since some of
the causal chains were speculated or unknown, the wing spar design was
questioned, existing airworthiness certificates were suspended and new
operating limits were placed on any reissued ones. The designer employed
external reviewers who found no problems with the design, but nevertheless
made changes to beef up the wing. (Does some of this sound familiar after
reading of the Zodiac problems?)

You can find some history on the RV-3 problems he

http://www.romeolima.com/RV3hq/Info/info.html

Scroll down to the "RV-3 wing spar background" section and review the
documents at the three links provided for additional background and detail.