Your approach is specifically one we do NOT want to follow. We have purposely setup our sales page and blog to allow people at the blog to get access to a heap of free information and opt-in if they choose.
Capture pages are becoming less and less relevant in my opinion, especially in the Internet Marketing niche. People are smart and don't like to be "marketed too", at least all the time.
The real power is building a relationship with your visitors and we achieve this with a multitude of videos on both sites, I mean just read the testimonials on our sales page (yes they are real!).
Our website is getting a lot of traffic these days, proof enough that our methods are working.
Capture pages do not increase value for the visitor, and only possibly for us.
Appreciate the time you have taken to mention it though and we have used them (capture pages) in non IM niches to good effect.