Ask HN: PG temporal schema using inheritance and the rule system

I have implemented a proof-of-concept of a SCD type 2 temporal database system (with valid-time only) using postgres' table inheritance, exclude constraints and the rule system.

I am planning to use this system as a backend for a set of Active Record classes (in a Ruby on Rails application).

The code and a quick discussion is here: https://gist.github.com/2563820

Which pitfalls am I overlooking?

Thanks,

~vjt