Using CloudFlare as the only load balancer
Yes, CloudFlare can load balance your traffic. However this opens up some issues that you have to be willing to deal with:
- CloudFlare does not automatically provide sticky sessions. This means anyone that goes to you site may land on one server for one request and another for another request. This has implications with any user logins or anything that requires server sessions. But there are other solutions for this, and if you are just serving up static content this is not a problem.
2. CloudFlare does not provide automatic failover nor monitor the origin servers, so if one goes down, web requests will still be directed to the dead server and users will see a CloudFlare error page. However, there are other ways to perform this monitoring and remove the failed server from your DNS, see Can CloudFlare perform automatic failover to a different backend?
As long as you can deal with the 2 items above then it works great. In fact I use this setup today for multiple sites that have survived the front page of HackerNews.