The rails DB integration lets you use the database directly whenever it suits you. At that point it's more a matter of arranging your data so that it lets you work around the key pain points. Since you can access the data directly when needed in rails, how will a new framework help if your problem is in the database?

Since Ruby gives you such great flexibility, it wouldn't be that hard to hack things around a bit to redirect data requests to some other source.

I don't see that as the problem.