Spam and exploit attempts are bound to rise given the sites increasing popularity, in the long term this will likely become more of an issue . The only thing I would add to this suggestion would be to also include Audio Captcha's for the visually impared, there have been a few instances where they've been excluded because no method for hearing a captcha was implemented.
Something else to consider though is that there have been some groups, operating out of India for example, that pay people to bypass captcha's to post spam. I beleive tigsource also uses a series of community questions to thwart drive-by posters who don't at least spend a little time getting familiar with the indie scene and the community.