If the 0.4 percentage points increase will get you more earnings than its costs, then yes it's worth it. The other way to look at this: if the cost of bringing

If the 0.4 percentage points increase will get you more earnings than its costs, then yes it's worth it. The other way to look at this: if the cost of bringing the site up (e.g. salary of having a sysadmin always on call) is higher than the increase in availability, then again it's worth it. So I agree with your final conclusion: it is worth it.