We travelled down this past Saturday with Sunwing. Interestingly, there was no pre-clearance (does Sunwing not use the US pre-clearance facilities?) and when we arrived in Orlando we went through US customs. The line up was miserably long and the CBP officer seemed like he'd never dealt with an I-194 before. Although he didn't send our family through to secondary, he kept shuttling back and forth to ask questions of his superiors. After some electronic finger printing, a mug shot and 1 hour and 30 or so minutes, we were finally waved through.