After weeks of this silly new letter code on Blogger comments driving me crazy, I've finally figured out how to remove it!
You just need to resort back to your old dashboard, so www.blogger.com/home instead of www.draft.blogger.com/home. Then you can go into settings just like before and opt out of the Captcha.
Anyway I know that there are others of you struggling with this so I thought I would share this little tip.
Happy blogging :)