Your chances of surviving a slashdot or digg effect is entirely based on how optimized your scripts are and what kind of content you provide.
In perfect scenario A, if you host only an average static site made of .html files, you'll be fine.
If you host an average dynamic site on nicely made software, such as wordpress, you will be mostly fine. You may want to install wp-cache or similar, and then you'll be fine. (We recommend wp-cache to all users anyhow!)
If you host an average dynamic site on more "CPU-hungry" software, such as Drupal, Moveable Type, or Ruby on Rails, you will probably have trouble and could get disabled. We will attempt to limit your connections first, but if your site is using a large amount of CPU processing per page view, we may eventually have to disable your site. A cache plugin for your software is a must. FastCGI is also recommended, if you know how to implement it.
If you are serving a static site with large file downloads, we might have to limit your simultaneous connections or your total speed, if either one is excessive. This is common with slashdot effects on sites that offer multi-megabyte files.