Earlier quoted context omitted.
It's very likely what you did made ranking a correlative rather than causative effect. Most of these comments were probably no-follow, and even if not, devalued b/c below the fold - reasoning: the Reasonable Surfer patent - http://www.seobythesea.com/2010/05/googles-reasonable-surfer... I agree that this can be helpful, but the way it is framed in this article is dangerous, because it can easily be misinterpreted.
While I don't condone the methods posted in this case study, I think that it goes to show that no-follow links do have value, that your on-page doesn't have to be perfect, and that the types of links that you claim don't work actually do. http://serpfu.com/case-study-insurance/ Once again, let me clarify that I don't condone the type of link building here, but I don't think that you can argue that it doesn't work.
Sounds like blog comments aren't the way to go.
They also advertise this service as "Penguin safe." Maybe if you launch your site between algorithm updates. You can definitely rank with these kind of links, but you will get torched eventually. This is not a long or even medium term strategy for what most of consider a startup.