What is the practical limit to the number of roles in a DNN system?

When I launched our DNN instance I was new to the platform and ended up creating a another DB table to store which customer the user was a member of.  Now I'm realizing how much more flexible my code would be if I was simply using roles instead.

We have thousands of customers - could the DNN framework handle that number of roles and/or social groups?

Thanks,

Greg