Did either of you guys try LamyUSA's customer service to reconcile the problems with your pens? Remember they have a lifetime warranty. I have several and have never had any trouble at all, in fact were it not for Waterman Lamy would be my favorite pen company.
Also, Good fountain pens rarely, if ever leak, I have a collection of cartridge/converter models (mostly Parker, Sheaffer, and Lamy) and have never had one leak. Stick to a good cartridge or converter filler and there should be no trouble. Most pens that leak are those that fill from the bottle via a complicated mechanism (ex. certain Mont blancs), the rubber/plastic seals wear with time and then you have a leak. The recommendation of using a ballpoint for carbon paper is very true, I personally wouldn't use a fountain for that.