Indeed the protoyping takeaways would be interesting. It's quite rare in real world apps to prototype a system in several languages to pick one. From the text,

Indeed the protoyping takeaways would be interesting. It's quite rare in real world apps to prototype a system in several languages to pick one. From the text, to me it seems more likely to me that there were several prototypes for other reasons, and they might not be functionally or architecturally equivalent enough for direct language comparisons.