Tenants with +700 & ~550 Credit Score - Accept?

[Matthew Farmer]

Hi - Recently had an application on a property with a really strong candidate and a less strong one. They are engaged, with the strong candidate having +700 credit and single handedly has a 5x gross income to rent just on her salary alone..she also just graduated college as an RN and could get the house on her own merit. However, the other tenant over the age of 18 (spouse), has a credit score in the 500's and appears he is in a debt resolution program (basically negotiating credit cards down)...don't see any evictions, or judgements filed on him. All prior references check out also, so only red flag right now is the credit score on this applicant.

I do have other quality applicants without this issue, but these 2 individuals are willing to sign a long term lease where I have an impression they could be in the home for +4 years if things go well, which would be great savings on vacancy costs. 

Should I take a gamble?