Use a mortgage with a 5 year balloon or a line of credit?

[Robert Renne]

I am going to buy my first duplex but I was wondering if anyone had any advice on whether to use a mortgage with a 5 year balloon or just use a credit line offered by a different bank. The credit line allows 3 years of interest only payments and as much on principle as I wish. After which I would need to refinance the house for a standard loan. Does anybody have any advice as to why one would be better than the other? Or experience with a similar situation? Any advice would be appreciated. Thank you in advance.