Because this is a huge problem for existing third-party wikis (and because we don't have any usage statistics), I'm not sure, which plan we should choose. That's why I sent this e-mail out, to get (hopefully) some responses and opinions.
We do have stats. There are 308 people using ReCaptchaNoCaptcha ( https://wikiapiary.com/wiki/Extension:ReCaptchaNoCaptcha ). There are about 165 people using plain ReCaptcha (https://wikiapiary.com/wiki/Extension:ReCaptcha - note, exclude the one's using version 0.1. That's a different extension with the same name).
Obviously this misses some wikis, but should provide a ballpark figure. I imagine most of the people still on ReCaptcha simply haven't bothered or are unaware that they can update to the new one.
-- Brian