I want to change my all my blog comments links to Dofollow and attract more comments. I will use good plugin for restrict spam comments and accept good comments only. It creates any problem in Google or other search engine.
It is the best way to increase more and more traffic. But only you can loss PR. Because the PR will be distributed in the websites added in the comment as anchor text.
It doesn't affect your seo for google and other search enginees, and you will also get more comments and traffic.
To be honest, I've seen a lot of blogs with "dofollow" and a lot of blogs with "nofollow" and I really haven't seen an increase in quality comments. An increase in spam comments, maybe, but the amount of quality increase is rather non-existent.