I don't think signing up yearly is necessarily a bad idea. It can often save the customer some real money. However, I would look at their TOS to see that if the customer were not happy and decided to cut their losses and leave, do they offer a prorated refund. If not, I wouldn't sign up for a yearly account, but I think any hosting business that is willing to back up their service with cold hard cash, would offer a prorated refund to those customers.