I have no insider knowledge, but I'm going to guess that they even crawl using actual Chrome browsers once in a while... and penalize deviations from what you s

I have no insider knowledge, but I'm going to guess that they even crawl using actual Chrome browsers once in a while... and penalize deviations from what you serve to the GoogleBot... and also factor in response times for either. I don't think any single person can predict/know what's actually going on at this point.