300 CPU·seconds is a lot of processing. If you are using anything like that amount of processor time in an hour, either you're supporting more than "a couple of users" or your software is either (a)highly inefficient or (b)doing something other than Free Hosting is designed to support. This is not an application hosting platform, it's for web sites, not web applications.
And, frankly, an all-singing, all-dancing Content Management System (they're designed for corporate communications workflow, approval and publication) with every plugin under the sun is wicked overkill for most web sites—if you're running a blog-type site that is hitting the HRU limit without your site being Reditted or Slashdotted, you're using the wrong platform. That's your choice, of course, but you'll find that paying for hosting will be the only way to make it work.