hello,
there is a few things about Go which make it very suitable for off-page optimization tasks. Since you use much less memory than in PHP etc. you can consolidate much more stuff on one server without it breaking into sweat, The templating system is amazingly good it isn't ruby on rails but it never feels clumsy and it's much faster.
often customers in SEO don't understand a lot about the subject, so you can make sure that you have some fancy page for them to look at although it's the same structure than other pages.
stuff like semantic tag elements in your page you handle yourselves.
So you plainly can throw some IPs on the server
- redirect domain names to those IPs so that they appear on your server
- have Go handle the hostname in the httphandler
- and then decide which of the zillions of sites you have stored in the database needs to be shown.
it is even easily possible to handle several servers without need for MySQL Master/Slave replication by simply handling the MySQL as storage mechanism on each server locally and have a master server send binary gob packages to the client server this way you can handle much more data in a simplistic fashion.
In a Nutshell Go is fun and usefull.
these are the relevant libraries to get you started.