1) One of the advantages of Airfoil is that you can significantly change the design and structure of your page, rather than just superficial changes to copy, colors etc. In my opinion it's much easier to make drastic changes directly to the HTML rather then messing around with an in-browser WYSIWYG HTML editor. Of course you can also use our variant tags to change what javascript is loaded, drastically effecting the content of single page apps.

2) We rolled out two variants for the headline copy on airfoil.io, and even in our relatively small sample set (less than 2k uniques so far) we've seen a dramatic difference in conversion (25% vs 10%)

3) You can add additional test cases, and change probabilities, by editing the app's config.yml file. The relevant configuration might look like this:

  variants:
    a: 0.2
    b: 0.2
    c: 0.6