I love older dogs, so I can't really give an unbiased opinion. If you think she's a good fit with your family, and if she's in good health I can't think of a good reason not to adopt her. My Li'l Girl is 9 years old, and has no health issues whereas Spook, our 4 year old mixed breed, has epilepsy and pyloric stenosis.
So, my best advice is go with your instincts.
So, my best advice is go with your instincts.