I haven't had a problem either, in fact they're the ONLY tubes I get now (if I need them, which isn't that often - certainly not as often as you [OP] indicate).
BTW, I *love* the french presta valve - 60mm with no tread! Just a solid brass valve with nothing to loosen on the ride, fits snug through the valve hole in the rim - perfect! If only all tubes were like these.