Are social bookmarking sites the best source of traffic for a niche blog?

[jessekanclerz]

I have been blogging since mid-December of last year, however the only promotion I had been doing was adding comments on blogs with a similar focus. My niche is marketing, with a leaning toward direct and email marketing. I had been receiving some traffic from the back links with the majority coming from keyword searches - these types of visitors appeared to be somewhat engaged with the content staying an average of 3-4 minutes on my site.

A few days ago I took two of my better posts and put them on Digg. I did not receive much traffic from this listing, however I've noticed an explosion of traffic from Reddit. The other day my analytics clocked 117 unique visitors with 100 of them coming from Reddit.

However, the Reddit visitors are not engaged with my site. They leave almost instantaneously, skewing the bounce rate and average site visit time extremely high.

In my opinion it seems these social bookmarking sites pander to readers looking for breaking news and more general content.

In light of these observations should a niche blog (especially one not concerned with generating advertising revenue) focus more on increasing organic traffic or rely on artificially generated traffic from Digg, Reddit in the hope of attracting its narrower target readers from the mass of visitors?

What are your opinions?