I've been working with a RoR shop for the past 7 months and have been happy so far with the products they have developed for me; I have done all the wire framing and product descriptions and they have done a good job executing in a timely fashion. We use github for all projects. To date we have had a contract relationship. I have been approached by potential investors and I am starting to think about forming a company and hiring this team on a more permanent basis. At this time, I'm trying to get a better sense for the "quality" of their development work and am wondering about techniques that could be effective.
As I know most of the audience here is technical, i'd really appreciate your input.
Ask them what communities they converse with, and see if they are well respected.
Use metrics tools on the products to find out how efficient it is at runtime.
None of this is as important as having a good relationship with them. If they are reliable, make good shit and you are comfortable with their rates, thats good.