I have been carrying the Swisscard for over 3 years now...the pen has come into use in MANY situations, something other cards do not have. Also the toothpick (having braces...) has been quite useful when I'm at a restaurant, away from home. It's quite slim and is probably the lightest/slimmest out of them all, also having more tools than the others, AFAIK.
IMO, what is the point of having a strong cutting blade (like the SOG, SpyderCard and others) when you already carry 1 or more "real" knives on you? Unless you ARE looking for a replacement for the times when you can't carry your other knives....but for opening boxes, envelopes and other small tasks, the small knife in the SwissCard handles them fine.
Warthog