I've run both the CK61's and CK63's on my own and with a friend (who owns them as well) and if you're planning to run open (assuming you are with the bodies), I'd lean towards picking up the hypercards. I own both and went the CK61 route for hat mounting, however, I quickly learned that the CK63's are a better choice when running open as I was experiencing sound "drop off" outdoors at some shows. Many people around here like the CK63's over the CK61's with the general thought that they "sound better" and really shine at a distance (assuming you're running near the board). Even in weirder rooms (ones where there is no "great" place to run open), the CK63's have a better rejection rate for chatty people over the CK61's (have run both in close proximity).
CK63's are my vote. If you're going to buy new, keep in mind that the best price I've been able to find is around US$480 for the pair (which is $20 more than what I paid for the CK61's).