It's not worth worrying much about what will happen when shit hits the fan if the fan isn't spinning yet. First, figure out how to get some power to the thing.
He's also optimized around his current setup and think that would carry over 1:1 to another platform. He has 24 unicorn workers now, so he thinks he needs 24 dynos on Heroku.
Whenever I've moved an app between platforms or server setups, I benchmark an individual instance and figure out your needs that way.
Also find it interesting how his current setup is all on a single server. So his entire service is one massive SPOF. On Heroku, he'd be highly available and horizontally scalable. How much does downtime cost him?
It's not worth worrying much about what will happen when shit hits the fan if the fan isn't spinning yet. First, figure out how to get some power to the thing.