I have been successful on multiple occasions and with multiple airlines (Cape Air, Seaborne, Intercarribean) making the connection in as little as 75 minutes and getting our boarding pass at the gate (though more comfortable with minimum 90 minute layover). And, this is with our flight into SJU has always being on a seperate ticket (SWA). We have never had to go outside security to the ticket counter. Of course this is with carry on only.