Can you describe the network infrastructure in finer detail? Specifically what type of load balancer are you running?
And what's peak RPS? Where are your network peaks? (I'm guessing major peak US Pacific and minor US Atlantic?)
But nowadays, from what I've read here on HN by SE devs in other threads, they're using lots and lots and lots of Linux: HAProxy, Redis, Nagios, etc.
I just double-checked the slide and although I didn't notice it at first, you can see that 'HA Proxy' and 'Redis' are mentioned.
The core Q&A is in C#/MS-SQL so that's probably not going to move to Linux anytime soon.