ALL drysuits leak, eventually. It's the nature of the beast -- you have a suit which has to be absolutely without a pinhole, and on which all valves must seat perfectly, and seals must fit perfectly, in order to be dry. As my dear friend Bob says, "All dry suits become wet suits, and then you get them fixed."
Some materials seem to have more of a tendency to develop pinholes than others. Either this is true of the DUI suits, or it's just that so many people I know own them that I hear a lot of stories about seeps in DUI suits. My primary dive buddy has had his entire left SLEEVE replaced by DUI, because he had a leak that they just couldn't find and fix. They've worked hard at it for him, but it's a nuisance to have your dry suit in the shop repeatedly. And, as you point out, being wet in very cold water is a bit of a safety issue as well.
All dry suit owners, if they dive actively, eventually get good at finding and repairing leaks, no matter what brand they own.