Re-Captcha has been cracked ages ago. In fact, captcha is only effective if it is impossible tor humans to read the code and that is one of the biggest complaints with captcha, you can not read the darn things. Turing tests are just as effective and they don't drive your users crazy trying to decipher the darn things.
Drop the round previews, they look horrible. Go with the standard, it is the standard for a reason and by now users of the internet see them as a standard, meaning they understand see more what those little square images do since the work the same way on most sites. If it ain't broke, don't fix it.
I was talking to someone the other day and I told them that Dolphin 7.1 is really Dolphin 8, and that Dolphin 8 is really Dolphin 9; there are too many major changes in Dolphin for it to be a point release. Have you consider releasing it as 8?
Drop the round previews, they look horrible. Go with the standard, it is the standard for a reason and by now users of the internet see them as a standard, meaning they understand see more