Getting a high load rate out of WordPress is heavily dependent on using a cache engine.Also using say the CloudFlare free plan will allow you to support considerably more by having your static content delivered from their CDN. Using WP Super Cache, CloudFlare and a C2 you can handle hundreds to thousands of pages per second depending on exact configuration and website complexity etc. Using https will lower the limit but still higher than most will need. 100 per second is abut 250 million his a month! Without a content delivery network you should still be in the tens to hundreds per second if served from server cache.
My feeling is that C1s are a bit slow for all but the most basic static cached WordPress site. WordPress is a resource hog. But for some sites they’d be okay.
It’s relatively easy to migrate a WordPress install from a C1 to a C2 but it’s not quite a single click operation.