The pay per tweet system is quick and easy. With only 140 characters to tweet, your writing time is minimal or nonexistent. Whereas under the Pay Per Post system, you need to review a website and create a well written post.
In order to be qualified for a pay per post opportunity, your blogs PR also needs to be relatively high. It is very hard to get a high PR for a blog. The PR is determined by google and not by you.
In contrast, the PR of your twitter profile irrelevant. Your profile is qualified and eligible based upon your content and your number of followers. These factors are much easier to control than the PR of a blog.
You can start blog a blog and a twitter profile for free. In fact, you can feed the results of the blog to your twitter profile. So if you already have a blog, you already have relevant twitter tweet material and a following.
To start a twitter profile from scratch is much easier and faster to do and develop than a blog.
