To properly size a chain, run the chain around the big chainring and the biggest cog (not through the rear derailleur), find the point where the chain can be connected, and then add one inch.

I think you guys should take your bikes to the LBS and have them check out what's going on, the problem you describe really could get you hurt.

FWIW, I'm using a Connex connector link with my Centaur 10 speed chain, no problems thus far. Granted, it isn't very reassuring that both the Campy instructions and the Wipperman instructions advise against this-