+1, i am using it now, and when i wasn't using this i daily got 30-40 spammers around my forum spamming alot. I'm now very happy with this captcha
This does not prove anything except that spambot users and developerss are not interested in your resource.
This is called
protection by or due to obscurity
Commercial spambots come with databases of webresources (forums, blogs, etc.) and used antispam protections
So, both spambot developers target to crack first of all most popular protection methods and spambot users target to the most popular webresources.
If someone would change antispam methods even using the cracked ones regularly, the effect will be the same, there will be mismatch between tried by bots cracking techniques and installed protection until spambot databases get actualized. If you change protection frequently spambot databases will always be out of sync and, if you are not popular, get out of radar.
KeyCAPTCHA is simply not popular to waste time for it.
There are many publications how to crack it, for example:
Also, I would not trust my webresources and install on them backdoors to external online services whose creators are unidentifiable and untraceable. KeyCAPTCHA operated first under the title of fake Russia-based Joint Stock ITNP company. Now under US-based Mersane, still from Russia.