I think one of the biggest things to consider in your situation is also whether you want to be somewhere where they are solely (bio)Statistics-focused, or whether you'd prefer a program that also incorporates Epidemiology and Bioinformatics--I'm guessing you won't get as much of a Theoretical Statistics background, but you'd learn about other interesting things. And then consider what you want to do afterwards: do you want to be a professor? It might be best to have that theoretical background in that case. But if you're most interested in Applied Statistics, the Dartmouth program would give you a lot of tools to be able to do effective research in the field.
I'd say it's unranked because it's new, and also because it is kind of an "interdisciplinary program". If there are faculty who are well known in their fields, that's a good sign.