I'm hoping I got a faulty set and that Cutter will replace the three 4-packs that I bought in 2008. At first the tubes would hold air for about 48 hours, then only 24, then finally only 30 minutes. Made it to a friend's house having to constantly repump the whole way. We checked for leaks, but there were none that we could find. Finally we stuck the whole tube in a bucket and what do we see? Bubbles coming slowly out of the top of the valve itself, which was screwed down tight. This ended up happening four more times, one time stranding me at 2:00am. If that valve can get fixed, then these will be worth the price. Otherwise, be prepared to pump often.
EDIT: Tubes are getting replaced via an RMA. Helpful gear expert said via chat that the Cutter stuff has improved recently. Will update when I get the replacements.