I think it's just a matter of respect to wear a suit...i did and passed my interview. Not because of the suit, but because of me. My reasoning for not even debating on wearing jeans to an interview was that I respected the profession and trade. Now, would you walk into any other interview for any other career wearing jeans and t-shirt? Probably not, unless you didn't really want the job in the first place. Working for the CF is a respectable profession and as a fed. gov. employee on top of that, deciding on wearing a suit to show you respect it in an interview would work more to an advantage then not....
just my .02