I did the change because of two reasons:
Notifications for comments. When Google introduced Google+ comments to Blogger I did the switch and for some unknown reason I am not receiving notification for comments on articles. I have spent some time trying to fix this problem without success.
Syntax highlighting for code snippets. I was doing HTML exports from my text editor to include in blog posts, followed by a bit of HMTL fiddling, which is not always fun.