So my experience - in two attempts to use SDC were unsuccessful. Most likely due to busy route JFK<>PTY and staff.

Outbound - I wanted to change from 9:55am to 1:55am departure from JFK to PTY. Calling the desk indicates due to my low SPECIAL fare no seats in that fare class were available. I asked could I goto airport and just sit there as a stand-by - she stated yes but if I got on I would have to pay a $140 change fee for stand-by at airport? I'm doubtful since there website indicates only $25 but didn't chance it at 1:55AM.

Inbound - checkin at POS with connection from PTY-JFK next morning but an evening flight out of PTY was available for same night. The counter person in POS indicates because I was upgraded to Business (PTY-JFK) - now shown as an R fare which is not availability and if I want to downgrade to Econ I must switch to regular Y I would have to pay the change fee plus fare difference. I'm doubtful my 1K status factored in whatsoever. Upon arrival in POS - the Copa Club personnel indicated no seats available and didn't offer I could go stand-by at gate and I didn't even ask at that point.

In my opinion - it probably works on connections from PTY elsewhere and non-busy holidays (Passover and/or Easter) but not my experience in the past 4 days.