If you choose a host with a provem track record (which I highly recomend), then they've likely been in business for well over 1 year. Then you shouldn't have to worry about them "burning you". I would base my decision on the discount offered for paying yearly, and my own cash flow... whether I could afford to pay yearly. If the discount is good enough, and I have the money, then I'll pay yearly.

All hypothetical of course.