I have too... but gotta tell you, the online place was far more cheerful and patient with my questions!
They can't 'tune up' the Cobra unit (looks extremely sexy, and it very transferable from vehicle to vehicle with their little adapter box thingie). They can tune up the Uniden and now I am kicking myself for not getting my 520 tuned from the grumpy guys when I could. I am sure if I could get their attention at the counter they would be happy to take my money and get it back to me in a week or two.