The comparison is reasonable as long as you test against an equivalent feature-set on each platform. It might actually be an interesting exercise to gradually

The comparison is reasonable as long as you test against an equivalent feature-set on each platform. It might actually be an interesting exercise to gradually layer more features on top (such as the dispatcher chain and different templating/ORM layers) to discover inefficiencies in the various frameworks by comparing the relative performance impact. E.g. if you involve the dispatcher and Django suddenly gets 20% slower but Rails only 10% slower then that might hint at an inefficient dispatcher-impl in Django.