This comes up all the time, the best thing to do is use it to your advantage.
I assume your SaaS offers support, if you're a small team, when they call they will always speak to someone they have spoken to before, if you're a one-man-band, they are speaking to the CEO of the company every time they have a query. They don't have to wait for decisions to filter through, they will get an immediate response.
If they're worried about committing because you might go bust, offer a rolling monthly contract with the option to have 2 month free if they sign up for a year.
You'll be surprised how many go for the year after 2-3 months of paying full price.
Edit: Just to be clear, they aren't nightmare customers - they are within their right to know who they are doing business with. Just don't be ashamed if you're small, turn it around.