I think code maintainability has less to do with the language than with the architecture chosen by the developers.

Try to explore (save alone, maintain) a complex Python application like Plone with its multiple inheritance. And then read the code of a modern MVC Rails application. You'll see what I mean.

And your statement that Ruby is only marginally more readable than Perl is very surprising. Ruby is a vast improvement in terms of clarity over Perl and is on par with Python there.

the idea that ruby is a blub language while python is a foo language is laughable. Python has it's issues as well. New style classes vs old style classes. These types are treated differently than those types in terms of default behaviour. Decorators are not the easiest thing in the world to read. Metaclasses are another example.

In my opinion ruby's syntax is simpler from a users point of view and equally as powerful. This may be my bias, but a fair assessment is that they are fairly equal

Speaking from experience: I coded many thousands lines of Ruby code for my startup all alone. Then we raised seed, and hired a few additional developers. Two of them joined my project and took over the development from me. They're both very experienced programmers, but had no prior Ruby experience. It took them less than a month to become productive. Srsly. In short, if you write good code and bring in good developers, Ruby probably isn't going to be a problem.