My experience with nexus applying inland and visiting the states has been positive. Once I received my open work permit, I took that permit to the nexus office. They changed my residency status to Canada. I don't even pause when crossing the border flying in now. If you have nexus my personal experience is it isn't a problem. Your mileage may vary.
Canuck78 knows his stuff; so I'd heed his warnings if you don't have nexus. Nexus a computer passes you. No nexus you are at the mercy of people. People get cranky and ask more questions.
