Opinion is: it's a great idea. Having the users with single sign on built into a component will help allot particularly for adoption of those not so programmer savy on a Joomla platform.
Suggestions: One of the benefits of Joomla integration is the ability to extend the reputation component into other Joomla pages. For instance, people who comment on a blog post should be rewarded with reputation (for involvement and have a "read 25 blog posts" badge).
The reputation management system is critical for marketers because it identifies who is the most involved, in what way (through badges) and allows a marketer to specifically tag them with Google remarketing tags to advertise to them through the GDN or through YouTube's TrueView advertising platform.
I know that's a bit of a tangent, but I'm very keen to see this plugin developed.
Have you got a github URL? I may not be able to contribute, but I can try to offer support.