Haven't read the whole thing over, but they make no mention of performance comparisons in the conclusion. How could you miss that!
I've presided over two rails websites in the past and topping out at around 15req/s on average was not fun. Rewriting to Django and getting 45req/s and less memory usage was definitely worth it. (I'd rate my development experience in other areas to be about equal)
I'm curious: did you consider switching to another Ruby Web framework?